Patterning of multi-depth optical devices

Abstract

To provide methods for patterning of multi-depth layers for fabrication of optical devices.SOLUTION: A method of forming an optical device comprises: disposing a resist layer over a device layer disposed over a top surface of a substrate, the device layer having a first portion and a second portion; patterning the resist layer to form a first resist layer pattern having a plurality of first openings and form a second resist layer pattern having a plurality of second openings; and etching exposed portions of the device layer defined by the plurality of first openings and the plurality of second openings. The first openings form at least a portion of a plurality of first structures within the optical device, and the second openings form at least a portion of a plurality of second structures within the optical device.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001]

[0001] Embodiments of the present disclosure relate generally to optical devices. More particularly, embodiments described herein provide multi-depth layer patterning for the fabrication of optical devices. [Background technology]

[0002]

[0002] Optical devices can be used to manipulate the propagation of light by spatially varying the structural parameters (e.g., shape, size, orientation) of structures in the optical device formed on a substrate. Optical devices provide spatially varying optical responses that shape the optical wavefront as needed. These structures in optical devices alter the propagation of light by inducing localized phase discontinuities (i.e., abrupt changes in phase over distances smaller than the wavelength of light). These structures may be constructed from various types of materials, shapes, or configurations on a substrate and may operate based on various physical principles.

[0003] Fabrication of optical devices requires the formation of structures from device layers disposed on a substrate. However, the desired properties of the fabricated optical device may require the structures to have varying depths. Forming structures with varying depths may require patterning multiple adjacently disposed layers on the substrate. Therefore, there is a need in the art for a method for multi-depth layer patterning for fabrication of optical devices. Summary of the Invention

[0004] A method for multi-depth layer patterning for the fabrication of optical devices is provided. In one embodiment, a method is provided that includes disposing a resist layer on a device layer disposed on a top surface of a substrate, the device layer having a first portion having a first height above the top surface of the substrate and a second portion having a second height above the top surface of the substrate; patterning the resist layer to form a first resist layer pattern having a plurality of first openings formed on the first portion of the device layer and a second resist layer pattern having a plurality of second openings formed on the second portion of the device layer; and etching exposed portions of the device layer defined by the plurality of first openings and the plurality of second openings, wherein the plurality of first openings in the first resist layer pattern are configured to form at least a portion of a plurality of first structures in an optical device, the first structures having a first depth relative to the top surface of the substrate, and the plurality of second openings in the second resist layer pattern are configured to form at least a portion of a plurality of second structures in the optical device, the second structures having a second depth relative to the top surface of the substrate.

[0005] In another embodiment, a method includes disposing a hard mask over a device layer disposed over a top surface of a substrate, the device layer having a first portion having a first height above the top surface of the substrate and a second portion having a second height above the top surface of the substrate; disposing a resist layer over the hard mask, the resist layer having a top surface parallel to the top surface of the substrate; patterning the resist layer to form a first resist layer pattern having a plurality of first openings formed therein over the first portion of the device layer and a second resist layer pattern having a plurality of second openings formed therein over the second portion of the device layer; and forming a resist pattern by the plurality of first openings and the plurality of second openings. a first device layer segment configured to form at least a portion of a plurality of first structures in an optical device, the first structures having a first depth relative to an upper surface of a substrate; and a second device layer segment configured to form at least a portion of a plurality of second structures in the optical device, the second structures having a second depth relative to an upper surface of the substrate.

[0006] In yet another embodiment, a method includes disposing a planarization layer over a device layer disposed over an upper surface of a substrate, the device layer having a first portion having a first height above the upper surface of the substrate and a second portion having a second height above the upper surface of the substrate; disposing a resist layer over the planarization layer; patterning the resist layer to form a first resist layer pattern having a plurality of first openings formed therein over the first portion of the device layer and a second resist layer pattern having a plurality of second openings formed therein over the second portion of the device layer; and etching exposed portions of the planarization layer defined by the plurality of first openings and the plurality of second openings. , exposing an unmasked first device layer segment of a first portion of the device layer and exposing an unmasked second device layer segment of a second portion of the device layer; and etching the first device layer segment and the second device layer segment, wherein the first device layer segment is configured to form at least a portion of a plurality of first structures in an optical device, the first structures having a first depth relative to an upper surface of a substrate, and the second device layer segment is configured to form at least a plurality of second structures in the optical device, the second structures having a second depth relative to an upper surface of the substrate. [Brief explanation of the drawings]

[0007]

[0007] So that the above-mentioned features of the present disclosure can be understood in detail, a more particular description of the present disclosure briefly summarized above can be had by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings depict only exemplary embodiments and therefore should not be considered to limit the scope of the present disclosure, as other equally effective embodiments may also be permitted.

[0008] [Figure 1A] 1 is a schematic perspective view of an optical device according to one embodiment; [Figure 1B] 1B is a schematic cross-sectional view of the optical device of FIG. 1A. [Figure 2A] 1 is a schematic perspective view of an optical device according to one embodiment; [Figure 2B] 2B is a schematic cross-sectional view of the optical device of FIG. 2A. [Figure 3] FIG. 1 is a flow diagram of a method for forming an optical device, according to one embodiment. [Figure 4A] 1A-1D are schematic cross-sectional views of a substrate during a method of forming an optical device, according to one embodiment. [Figure 4B] 1A-1D are schematic cross-sectional views of a substrate during a method of forming an optical device, according to one embodiment. [Figure 4C] 1A-1D are schematic cross-sectional views of a substrate during a method of forming an optical device, according to one embodiment. [Figure 4D] 1A-1D are schematic cross-sectional views of a substrate during a method of forming an optical device, according to one embodiment. [Figure 4E] 1A-1D are schematic cross-sectional views of a substrate during a method of forming an optical device, according to one embodiment. [Figure 5] FIG. 1 is a flow diagram of a method for forming an optical device, according to one embodiment. [Figure 6A] 1A-1D are schematic cross-sectional views of a substrate during a method of forming an optical device, according to one embodiment. [Figure 6B] 1A-1D are schematic cross-sectional views of a substrate during a method of forming an optical device, according to one embodiment. [Figure 6C] 1A-1D are schematic cross-sectional views of a substrate during a method of forming an optical device, according to one embodiment. [Figure 6D] 1A-1D are schematic cross-sectional views of a substrate during a method of forming an optical device, according to one embodiment. [Figure 7] FIG. 1 is a flow diagram of a method for forming an optical device, according to one embodiment. [Figure 8A] 1A-1D are schematic cross-sectional views of a substrate during a method of forming an optical device, according to one embodiment. [Figure 8B] 1A-1D are schematic cross-sectional views of a substrate during a method of forming an optical device, according to one embodiment. [Figure 8C]1A-1D are schematic cross-sectional views of a substrate during a method of forming an optical device, according to one embodiment. [Figure 8D] 1A-1D are schematic cross-sectional views of a substrate during a method of forming an optical device, according to one embodiment.

[0009]

[0018] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements common to the figures. It is contemplated that elements and structures of one embodiment may be beneficially incorporated in other embodiments without further description. DETAILED DESCRIPTION OF THE INVENTION

[0010]

[0019] SUMMARY OF THE DISCLOSURE Embodiments of the present disclosure relate to multi-depth layer patterning for the fabrication of optical devices.

[0011]

[0020] 1A is a schematic perspective view of an optical device 100. In one embodiment, the optical device 100 is a waveguide coupler, e.g., an augmented reality waveguide coupler. It should be understood that the optical device 100 described below is an exemplary waveguide coupler. The optical device 100 includes a substrate 101, a first grating 102 defined by a plurality of structures 103, and a second grating 105 defined by a plurality of structures 106. In one embodiment, the structures 103 and the structures 106 are nanostructures having submicron critical dimensions (e.g., nano-sized critical dimensions).

[0012]

[0021] FIG. 1B is a schematic cross-sectional view of the optical device 100 of FIG. 1A. The optical device 100 includes a plurality of structures 103 having two or more depths. As shown in FIG. 1B, a plurality of first structures 114 have a first depth 116 into a top surface 118 of the substrate 101, and a plurality of second structures 115 have a second depth 117 into the top surface 118 of the substrate 101. The first depth 116 and the second depth 117 are different. For example, as shown in FIG. 1B, the first depth 116 is shallower than the second depth 117. In one embodiment, the structures 103 are at an angle relative to the top surface 118 of the substrate 101. In another embodiment, the structures 103 are perpendicular to the top surface 118 of the substrate 101.

[0013]

[0022] 2A is a schematic perspective view of an optical device 200 having one or more structures 203 according to embodiments described herein. In some embodiments, the optical device 200 is a planar optical device, such as a metasurface. The one or more structures 203 are disposed on a substrate 101. While FIG. 2A illustrates the one or more structures 203 as having a square or rectangular cross-section, the cross-section of the one or more structures 203 may have other shapes, including, but not limited to, circular, triangular, and / or irregularly shaped cross-sections. In one embodiment, the structures 203 are nanostructures having submicron critical dimensions (e.g., nano-sized critical dimensions).

[0014]

[0023] 2B is a schematic cross-sectional view of the optical device 200 of FIG. 2A. The optical device 200 includes one or more structures 203, such as one or more first structures 214 and one or more second structures 215, disposed on a substrate 101. The one or more first structures 214 have a first depth 216 into the top surface 118 of the substrate 101. The one or more second structures 215 have a second depth 217 into the top surface 118 of the substrate 101. The first depth 216 and the second depth 217 are different. For example, as shown in FIG. 2B, the first depth 216 is shallower than the second depth 217. In one embodiment, the structures 203 are at an angle relative to the top surface 118 of the substrate 101. In another embodiment, the structures 203 are perpendicular to the top surface 118 of the substrate 101.

[0015]

[0024] Substrate 101 may be selected to transmit an appropriate amount of light of a desired wavelength or wavelength range (e.g., one or more wavelengths from the infrared to the UV region (i.e., from about 700 to about 1500 nanometers)). Without limitation, in some implementations, substrate 101 is configured to be approximately 50%, 60%, 70%, 80%, 90%, 95%, 99% or more transparent to the UV region of the light spectrum. Substrate 101 may be formed from any suitable material, so long as it can adequately transmit light of a desired wavelength or wavelength range and serve as a suitable support for an optical device. In some embodiments, the material of substrate 101 has a relatively low refractive index compared to the refractive index of the device material. Substrate choices may include substrates of any suitable material, including, but not limited to, amorphous dielectrics, crystalline dielectrics, silicon oxides, polymers, and combinations thereof. In some embodiments, substrate 101 comprises a transparent material. In one embodiment, the substrate 101 is transparent with an absorption coefficient less than 0.001. Suitable examples may include oxides, sulfides, phosphides, tellurides, or combinations thereof.

[0016]

[0025] In some embodiments, the optical devices 100, 200 described herein include first structures 114, 214 having a first depth 116, 216 and second structures 115, 215 having a second depth 117, 217 disposed in a substrate 101. In the described embodiments of the methods 300, 500, and 700 for forming the optical devices 100, 200, the substrate 101 has a first height 404 and a second height 405 (shown in FIG. 4A ). The first height 404 corresponds to the first depth 116, 216 of the first structures 114, 214 to be formed, and the second height 405 corresponds to the second depth 117, 217 of the plurality of second structures 115, 215 to be formed in the substrate 101.

[0017]

[0026] In other embodiments, the optical devices 100, 200 described herein include a first structure 114, 214 having a first depth 116, 216 and a second structure 115, 215 having a second depth 117, 217 disposed on a substrate 101. The first structure 114, 214 and the second structure 115, 215 are formed from a device layer 408. Prior to the methods 300, 500, and 700, the device layer 408 has a first height 411 and a second height 412. The first height 411 corresponds to the first depth 116, 216 of the first structure 114, 214 to be formed, and the second height 412 corresponds to the second depth 117, 217 of the plurality of second structures 115, 215 to be formed.

[0018]

[0027] 3 is a flow diagram of a method 300 for forming a portion of optical device 100, 200 according to an embodiment described herein. Figures 4A to 4E are schematic cross-sectional views of substrate 101 during a method for forming a portion of optical device 100 or optical device 200 according to one embodiment. The portion may correspond to one grating, such as first grating 102 or second grating 105, or the portion may correspond to the entire optical device 100 or optical device 200.

[0019]

[0028] Figure 4A shows an embodiment in which a resist layer 407 is disposed on a substrate 101. In one embodiment, the substrate 101 is patterned such that the substrate 101 has a first height 404 and a second height 405 to achieve first structures 114, 214 and second structures 115, 215 of various heights. Figure 4B shows an embodiment in which the resist layer 407 is disposed on a device layer 408, which is disposed on a top surface 118 of the substrate 101. In one embodiment, the device layer 408 is patterned such that the device layer has a first height 411 and a second height 412 to achieve first structures 114, 214 and second structures 115, 215 of various heights.

[0020]

[0029] In one embodiment, resist layer 407 comprises a silicon-containing material. In another embodiment, resist layer 407 comprises an organic material. Resist layer 407 is deposited on surface 101 through any suitable method (e.g., a liquid material injection casting process, a spin-on coating process, a liquid spray coating process, a dry powder coating process, a screen printing process, a doctor blading process, a physical vapor deposition (PVD) process, a chemical vapor deposition (CVD) process, a flowable CVD (FCVD) process, or an atomic layer deposition (ALD) process). The thickness of resist layer 407 is selected to coordinate the etching process and the resulting critical dimensions of structures 103. For example, a thicker resist layer 407 may result in smaller critical dimensions of structures 103. In one embodiment, resist layer 407 has a thickness ranging from about 50 nm to about 300 nm. In one embodiment, resist layer 407 comprises a first thickness 409 and a second thickness 410. The first thickness 409 may be greater or less than the second thickness 410. The first thickness 409 causes the first structures 114, 214 to have a first depth 116, 216. The second thickness 410 causes the second structures 115, 215 to have a second depth 117, 217.

[0021]

[0030] According to one embodiment, the device layer 408 includes, but is not limited to, one or more of titanium dioxide (TiO), zinc oxide (ZnO), tin dioxide (SnO), aluminum-doped zinc oxide (AZO), fluorine-doped tin oxide (FTO), cadmium stannate (tin oxide) (CTO), niobium oxide (NbO), zinc stannate (tin oxide) (SnZnO), silicon nitride (SiN), and amorphous silicon (a-Si)-containing materials. In one embodiment, the height of the device layer 408 ranges from about 20 nm to about 200 nm. As shown in FIG. 3, a resist layer 407 is disposed on the device layer 408 in step 301. The device layer 408 includes a first portion 424 having a first height 411 from the surface of the substrate and a second portion 425 having a second height 412 from the surface of the substrate. The first height 411 corresponds to the first structures 114, 214 being formed, and the second height 412 corresponds to the second structures 115, 215 being formed.

[0022]

[0031] The embodiment of Figure 4A illustrates a 1:1 etch rate, while the embodiment of Figure 4D illustrates an etch rate other than 1:1, where the resist layer 407 is etched at approximately the same rate as the device layer 408. In step 301, as shown in Figure 4A, the resist layer 407 is disposed over the device layer 408, which corresponds to the plurality of first structures 114, 214 and the plurality of second structures 115, 215 to be formed. In one embodiment, the resist layer 407 is disposed over the substrate 101, as shown in Figure 4B.

[0023]

[0032] In step 302, as shown in FIGS. 4C and 4D, the resist layer 407 is patterned to expose unmasked portions of the device layer 408. Patterning the resist layer 407 includes forming a first resist layer pattern 422 over a first portion 424 of the device layer 408, in which a plurality of first openings 420 are formed, and forming a second resist layer pattern 423 over a second portion 425 of the device layer 408, in which a plurality of second openings 421 are formed. The resist layer 407 may be patterned by a process including, but not limited to, nanoimprint lithography, photoimprint lithography, or any suitable process that exposes unmasked portions of the device layer 408. In the embodiment shown in FIG. 4D, a residual layer 413 remains after the resist layer 407 is patterned. In one embodiment, the residual layer 413 is removed through a dry etch process.

[0024]

[0033] FIG. 4D illustrates an embodiment in which an etch stop layer 406 is disposed on the substrate 101. The etch stop layer 406 prevents over-etching into the substrate 101. The etch stop layer 406 may be disposed by one of PVD, CVD, plasma-enhanced chemical vapor deposition (PECVD), FCVD, ALD, and spin-on processes. The etch stop layer 406 may be formed from any suitable material, so long as the etch stop layer 406 is resistant to the etching processes described herein. In one embodiment, the etch stop layer 406 comprises a nitrogen-containing material. In one embodiment, the etch stop layer 406 is a non-transparent etch stop layer that is removed after the waveguide coupler is formed. In another embodiment, the etch stop layer 406 is a transparent etch stop layer. The etch stop layer 406 has a depth of about 5 nm to about 50 nm. Although an etch stop layer 406 is shown herein, one or more embodiments are contemplated in which the etch stop layer 406 is absent.

[0025]

[0034] In step 303, as shown in FIGS. 4C and 4D , exposed portions of the device layer 408 defined by the plurality of first openings 420 and the plurality of second openings 421 are etched to form the plurality of first structures 114, 214 and the plurality of second structures 115, 215. The plurality of first openings 420 in the first resist layer pattern 422 are configured to form at least a portion of the plurality of first structures 114, 214 in the optical device 100, 200. The plurality of second openings 421 in the second resist layer pattern 423 are configured to form at least a portion of the plurality of second structures 115, 215 in the optical device 100, 200. The etching process may include, but is not limited to, at least one of ion implantation, ion beam etching (IBE), reactive ion etching (RIE), directional RIE, plasma etching, and thermal atomic layer etching. In some embodiments, the etching process utilizes an oxidizing etching chemistry. In other embodiments, the etching process utilizes a reducing etching chemistry. In one embodiment, the etching process utilizes one or more of oxygen, nitrogen gas (N), SiO, chlorine, and ammonia (NH)-containing gases. In another embodiment, fluorine-containing gases, such as fluoromethane (CHF), sulfur hexafluoride (SF), tetrafluoromethane (CF), fluoroform (CHF), and nitrogen trifluoride (NF), are used as etchants. Fluorine-containing gases are optionally supplied to the processing environment along with methane-containing gases, such as methane (CH) and dichlorodifluoromethane (CClF).

[0026]

[0035] 4E shows first structures 114, 214 and second structures 115, 215 formed in device layer 408, steps 301 through 303 are applicable to patterning substrate 101. In one embodiment, as shown in FIGS. 3 and 4D, device layer 408 is etched by an etching process to remove portions of device layer 408, and step 303 forms first structures 114, 214 and second structures 115, 215. In another embodiment, substrate 101 is etched by an etching process to remove portions of substrate 101, and step 303 forms first structures 114, 214 and second structures 115, 215.

[0027]

[0036] Figure 5 is a flow diagram of a method 500 for forming a portion of an optical device 100, 200 according to an embodiment described herein. Figures 6A-6D are schematic cross-sectional views of an optical device 100, 200 formed according to the method 500. The portion of the optical device 100, 200 may correspond to one grating, such as the first grating 102 or the second grating 105, or the portion may correspond to the entire optical device 100 or optical device 200.

[0028]

[0037] In step 501, as shown in FIG. 6A, a hard mask 609 is disposed on the device layer 408. The hard mask 609 may be disposed on the device layer 408 by one or more of liquid material injection casting, spin-on coating, liquid spray coating, dry powder coating, screen printing, doctor blading, PVD, CVD, PECVD, FCVD, ALD, evaporation, and sputtering processes. In one embodiment, the hard mask 609 is non-transparent and is removed after the optical device 100 or the optical device 200 is formed. In another embodiment, the hard mask 609 is transparent. In some embodiments, the hard mask 609 comprises any suitable imprint resist material (e.g., chromium (Cr), silver (Ag), Si3N4, SiO2, TiN, aluminum, and carbon-containing materials).

[0029]

[0038] In step 502, a resist layer 407 is disposed over the hard mask 609, and a device layer 408 corresponds to the plurality of first structures 114, 214 and the plurality of second structures 115, 215 to be formed. The device layer 408 has a first height 411 and a second height 412. In one embodiment, the first thickness 409 and the second thickness 410 of the resist layer 407 are different such that the top surface 610 of the resist layer 407 is parallel to the top surface 118 of the substrate 101. The top surface 610 of the resist layer 407 being parallel to the top surface 118 of the substrate 101 provides a planarized surface to improve the uniformity of the patterning and / or etching processes of steps 503 and 504.

[0030]

[0039] In step 503, as shown in FIG. 6B, the resist layer 407 is patterned to expose portions of the hard mask 609. Patterning the resist layer 407 includes forming a first resist layer pattern 422 having a plurality of first openings 420 formed therein over a first portion 424 of the device layer 408, and forming a second resist layer pattern 423 having a plurality of second openings 421 formed therein over a second portion 425 of the device layer 408. In step 504, as shown in FIG. 6C, the exposed portions of the hard mask 609 are etched to expose unmasked first device layer segments 612 of the first portion 424 of the device layer 408 and unmasked second device layer segments 613 of the second portion 425 of the device layer 408. 6D , the first device layer segment 612 and the second device layer segment 613 of the device layer 408 are etched to form a plurality of first structures 114, 214 and a plurality of second structures 115, 215. The first device layer segment 612 is configured to form at least a portion of the plurality of first structures 114, 214 in the optical device 100, 200. The second device layer segment 613 is configured to form at least a portion of the plurality of second structures 115, 215 in the optical device 100, 200.

[0031]

[0040] In one embodiment, the hard mask 609 is removed after the device layer 408 is etched. In another embodiment, the hard mask 609 remains on the device layer 408 after the device layer 408 is etched. Although FIG. 6D shows the first structures 114, 214 and the second structures 115, 215 formed in the device layer 408, steps 501 through 504 are applicable to patterning the substrate 101. In one embodiment, as shown in FIGS. 5 and 6D , the device layer 408 is etched by an etching process to remove portions of the device layer 408, and the first structures 114, 214 and the second structures 115, 215 are formed in step 504. In another embodiment, the substrate 101 is etched by an etching process to remove portions of the substrate 101, and the first structures 114, 214 and the second structures 115, 215 are formed in step 504.

[0032]

[0041] Figure 7 is a flow diagram of a method 700 for forming a portion of an optical device 100, 200 according to an embodiment described herein. Figures 8A-8D are schematic cross-sectional views of an optical device 100, 200 formed according to method 700. The portion of the optical device 100, 200 may correspond to one grating, such as the first grating 102 or the second grating 105, or the portion may correspond to the entire optical device 100 or optical device 200.

[0033]

[0042] In step 701, a planarization layer 810 is disposed on the device layer 408, as shown in FIG. 8A , where the device layer 408 corresponds to the plurality of first structures 114, 214 and the plurality of second structures 115, 215 to be formed. In one embodiment, the planarization layer 810 comprises an a-Si-containing material. The planarization layer 810 can be deposited by any suitable process, including, but not limited to, a liquid material injection casting process, a spin-on coating process, a liquid spray coating process, a dry powder coating process, a screen printing process, a doctor blading process, a PVD process, a CVD process, a PECVD process, an FCVD process, or an ALD process. The planarization layer 810 forms a top surface 812 parallel to the substrate 101, thereby preventing over-etching of the device layer 408 during an etching process. In step 702, a resist layer 407 is disposed on the planarization layer 810.

[0034]

[0043] In step 703, as shown in FIG. 8B, the resist layer 407 is patterned to expose a portion of the planarization layer 810. Patterning the resist layer 407 includes forming a first resist layer pattern 422 having a plurality of first openings 420 formed therein over a first portion 424 of the device layer 408, and forming a second resist layer pattern 423 having a plurality of second openings 421 formed therein over a second portion 425 of the device layer 408. In step 704, as shown in FIG. 8C, the exposed portions of the planarization layer 810 defined by the plurality of first openings 420 and the plurality of second openings 421 are etched to expose unmasked first device layer segments 612 of the first portion 424 of the device layer 408 and second device layer segments 613 of the second portion 425 of the device layer 408.

[0035]

[0044] In step 705, as shown in Figure 8D, the first device layer segment 612 and the second device layer segment 613 of the device layer 408 are etched to form a plurality of first structures 114, 214 and a plurality of second structures 115, 215. The first device layer segment 612 is configured to form at least a portion of the plurality of first structures 114, 214 in the optical device 100, 200. The second device layer segment 613 is configured to form at least a portion of the plurality of second structures 115, 215 in the optical device 100, 200.

[0036]

[0045] Etching may include, but is not limited to, one or more of ion implantation, ion etching, reactive ion etching (RIE), directional RIE, and plasma etching. In one embodiment, the planarization layer 810 has a greater etch selectivity than the device layer 408. While FIG. 8D shows the first structures 114, 214 and the second structures 115, 215 formed in the device layer 408, steps 701 through 705 are applicable to patterning the substrate 101. In one embodiment, the device layer 408 is etched by an etching process to remove portions of the device layer 408, and the first structures 114, 214 and the second structures 115, 215 are formed in step 705. In another embodiment, the substrate 101 is etched by an etching process to remove portions of the substrate 101, and the first structures 114, 214 and the second structures 115, 215 are formed in step 705.

[0037]

[0046] The embodiments described herein provide a method for multi-depth optical devices that minimizes defects related to over-etching and non-uniformity.

[0038]

[0047] While the foregoing is directed to embodiments of the present disclosure, other and additional embodiments of the present disclosure may be devised without departing from the basic scope thereof, the scope of which is determined by the claims that follow. The present application also includes the following aspects. (Aspect 1) 1. A method of forming an optical device, comprising: disposing a resist layer on a device layer disposed on an upper surface of a substrate, the device layer comprising: a first portion having a first height above the top surface of the substrate; and disposing a resist layer having a second portion having a second height above the top surface of the substrate; The resist layer is patterned, forming a first resist layer pattern having a plurality of first openings formed therein on the first portion of the device layer; and forming a second resist layer pattern on the second portion of the device layer, the second resist layer pattern having a plurality of second openings; etching exposed portions of the device layer defined by the plurality of first openings and the plurality of second openings; Including, the plurality of first openings in the first resist layer pattern are configured to form at least a portion of a plurality of first structures in the optical device, the first structures having a first depth relative to the top surface of the substrate; the plurality of second openings in the second resist layer pattern are configured to form at least a portion of a plurality of second structures in the optical device, the second structures having a second depth relative to the top surface of the substrate. (Aspect 2) 2. The method of claim 1, wherein etching the exposed portions of the device layer defined by the plurality of first openings and the plurality of second openings comprises at least one of ion implantation, ion beam etching (IBE), reactive ion etching (RIE), directional RIE, plasma etching, and thermal atomic layer etching. (Aspect 3) 3. The method of embodiment 2, wherein the device layer comprises one or more of titanium dioxide, zinc oxide, tin dioxide, aluminum-doped zinc oxide, fluorine-doped tin oxide, cadmium stannate, niobium oxide, zinc stannate, silicon nitride, and amorphous silicon-containing materials. (Aspect 4) 10. The method of embodiment 1, wherein an etch stop layer is disposed on the substrate. (Aspect 5) 5. The method of embodiment 4, wherein the etch stop layer is non-transparent. (Aspect 6) 2. The method of embodiment 1, wherein the first depth is shallower than the second depth. (Aspect 7) 2. The method of embodiment 1, wherein the plurality of first structures and the plurality of second structures are perpendicular to the top surface of the substrate. (Aspect 8) 2. The method of claim 1, wherein the plurality of first structures and the plurality of second structures are at an angle with respect to the top surface of the substrate. (Aspect 9) 1. A method of forming an optical device, comprising: disposing a hard mask over a device layer disposed over an upper surface of a substrate, the device layer comprising: a first portion having a first height above the top surface of the substrate; and disposing a hard mask having a second portion having a second height above the top surface of the substrate; disposing a resist layer over the hard mask, the resist layer having a top surface parallel to the top surface of the substrate; The resist layer is patterned, forming a first resist layer pattern having a plurality of first openings formed therein on the first portion of the device layer; and forming a second resist layer pattern on the second portion of the device layer, the second resist layer pattern having a plurality of second openings; etching exposed portions of the hard mask defined by the plurality of first openings and the plurality of second openings; exposing an unmasked first device layer segment of the first portion of the device layer; and exposing an unmasked second device layer segment of the second portion of the device layer; Etching the first device layer segment and the second device layer segment; Including, the first device layer segment is configured to form at least a portion of a plurality of first structures within the optical device, the first structures having a first depth relative to the top surface of the substrate; The method, wherein the second device layer segment is configured to form at least a portion of a plurality of second structures within the optical device, the second structures having a second depth relative to the top surface of the substrate. (Aspect 10) 10. The method of embodiment 9, wherein the first depth is shallower than the second depth. (Aspect 11) 10. The method of embodiment 9, wherein the hard mask is non-transparent. (Aspect 12) 12. The method of embodiment 11, further comprising removing the hard mask. (Aspect 13) 1. A method of forming an optical device, comprising: disposing a planarization layer over a device layer disposed over an upper surface of a substrate, the device layer comprising: a first portion having a first height above the top surface of the substrate; and disposing a planarization layer having a second portion having a second height above the top surface of the substrate; disposing a resist layer on the planarization layer; The resist layer is patterned, forming a first resist layer pattern having a plurality of first openings formed therein on the first portion of the device layer; and forming a second resist layer pattern on the second portion of the device layer, the second resist layer pattern having a plurality of second openings; etching exposed portions of the planarization layer defined by the plurality of first openings and the plurality of second openings; exposing an unmasked first device layer segment of the first portion of the device layer; and exposing an unmasked second device layer segment of the second portion of the device layer; Etching the first device layer segment and the second device layer segment; Including, the first device layer segment is configured to form at least a portion of a plurality of first structures within the optical device, the first structures having a first depth relative to the top surface of the substrate; The method, wherein the second device layer segment is configured to form at least a plurality of second structures within the optical device, the second structures having a second depth relative to the top surface of the substrate. (Aspect 14) 14. The method of embodiment 13, wherein an etch stop layer is disposed on the substrate. (Aspect 15) 14. The method of embodiment 13, wherein the first depth is shallower than the second depth.

Claims

1. 1. A method of forming an optical device, comprising: disposing a resist layer over a device layer disposed over an upper surface of a substrate; the device layer a first portion having a first height above the top surface of the substrate; and a second portion having a second height from the top surface of the substrate; disposing a resist layer, the second height being different from the first height, the resist layer having a first thickness over the first portion of the device layer and a second thickness over the second portion of the device layer that is different from the first thickness, the sum of the first height of the device layer and the first thickness of the resist layer being different from the sum of the second height of the device layer and the second thickness of the resist layer; The resist layer is patterned, forming a first resist layer pattern having a plurality of first openings formed therein on the first portion of the device layer; and forming a second resist layer pattern over the second portion of the device layer, the second resist layer pattern having a plurality of second openings; etching exposed portions of the device layer defined by the plurality of first openings and the plurality of second openings; Including, the plurality of first openings in the first resist layer pattern are configured to form at least a portion of a plurality of first structures in the optical device, the first structures having a first depth relative to the top surface of the substrate; the plurality of second openings in the second resist layer pattern are configured to form at least a portion of a plurality of second structures in the optical device, the second structures having a second depth relative to the top surface of the substrate.

2. 10. The method of claim 1, wherein etching the exposed portions of the device layer defined by the plurality of first openings and the plurality of second openings comprises at least one of ion implantation, ion beam etching (IBE), reactive ion etching (RIE), directional RIE, plasma etching, and thermal atomic layer etching.

3. 3. The method of claim 2, wherein the device layer comprises one or more of titanium dioxide, zinc oxide, tin dioxide, aluminum-doped zinc oxide, fluorine-doped tin oxide, cadmium stannate, niobium oxide, zinc stannate, silicon nitride, and amorphous silicon-containing materials.

4. The method of claim 1 , wherein an etch stop layer is disposed on the substrate.

5. The method of claim 4 , wherein the etch stop layer is non-transparent.

6. The method of claim 1 , wherein the first depth is less than the second depth.

7. The method of claim 1 , wherein the plurality of first structures and the plurality of second structures are perpendicular to the top surface of the substrate.

8. The method of claim 1 , wherein the plurality of first structures and the plurality of second structures are at an angle with respect to the top surface of the substrate.

9. 1. A method of forming an optical device, comprising: disposing a hard mask on a device layer disposed directly on the planar upper surface of a substrate, said device layer comprising: a first portion having a first height above the planar upper surface of the substrate; and disposing a hard mask having a second portion having a second height above the planar upper surface of the substrate, the second height being different from the first height; disposing a resist layer over the hard mask, the resist layer having a top surface parallel to the planar top surface of the substrate, the resist layer having a first thickness over the first portion of the device layer and a second thickness over the second portion of the device layer, the second thickness being different from the first thickness; The resist layer is patterned, forming a plurality of first openings over the first portion of the device layer to expose portions of the hard mask; and forming a plurality of second openings over the second portion of the device layer to expose additional portions of the hard mask; After patterning, a first patterned resist layer is formed on the first portion and a second patterned resist layer is formed on the second portion; patterning the resist layer to expose a portion of the hard mask and an additional portion, wherein a first total height from the planar upper surface of the substrate to a top surface of the first patterned resist layer is different from a second total height from the planar upper surface of the substrate to a top surface of the second patterned resist layer; Etching exposed portions of the hard mask; exposing a plurality of first device layer segments of the first portion of the device layer; and exposing a plurality of second device layer segments within the second portion of the device layer; etching the first device layer segment and the second device layer segment to expose at least a portion of the planar top surface of the substrate; forming at least a portion of a plurality of first structures in the optical device, the first structures having a first depth relative to the planar top surface of the substrate; forming at least a portion of a plurality of second structures within the optical device, the second structures having a second depth relative to the planar top surface of the substrate that is different from the first depth.

10. The method of claim 9 , wherein the first depth is less than the second depth.

11. 10. The method of claim 9, wherein the hard mask is non-transparent.

12. The method of claim 11 further comprising removing the hard mask.

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