METHOD FOR AMORPHOUS, HIGH-REFRACTIVE-INDEX ENCAPSULATION OF NANOPARTICLE IMPRINT FILMS FOR OPTICAL DEVICES

Embodiments provided herein provide for amorphous encapsulation of nanoparticle imprint films for optical devices. In one embodiment provided herein, a device is provided. The device includes a plurality of optical device structures disposed on a surface of a substrate. The plurality of optical device structures include a nanoparticle imprint material. The plurality of optical device structures further include an encapsulation layer disposed over at least a top surface and one sidewall of each optical device structure of the plurality of optical device structures. The encapsulation layer is amorphous or substantially amorphous. The encapsulation layer includes a niobium oxide. The niobium oxide is selected from the group consisting of niobium monoxide (NbO), niobium dioxide (NbO2), niobium pentoxide (Nb2O5), Nb12O29, Nb47O116, or Nb3n+1O8n−2, where n is 5 to 8.

BACKGROUND

Field

Embodiments of the present disclosure generally relate to optical devices for augmented, virtual, and mixed reality. More specifically, embodiments described herein provide for amorphous encapsulation of nanoparticle imprint films for optical devices.

Description of the Related Art

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

Augmented reality, however, enables an experience in which a user can still see through the display lenses of the glasses or other HMD device to view the surrounding environment, yet also see images of virtual objects that are generated to appear as part of the environment. Augmented reality can include any type of input, such as audio and haptic inputs, as well as virtual images, graphics, and video that enhance or augment the environment that the user experiences. As an emerging technology, there are many challenges and design constraints with augmented reality.

One such challenge is displaying a virtual image overlaid on an ambient environment. Optical devices including waveguide combiners, such as augmented reality waveguide combiners, and flat optical devices, such as metasurfaces, are used to assist in overlaying images. Generated light is propagated through an optical device until the light exits the optical device and is overlaid on the ambient environment.

The optical devices may include an encapsulation layer disposed over a top surface and at least one sidewall of the optical device structures. In some instances, the encapsulation layer must have a refractive index greater than or equal to 2.0, i.e., a high refractive index. However, cracks in the encapsulation layer may form when the encapsulation layer is disposed over crystalline or nano-crystalline optical device structures formed from nanoparticle imprint films. The cracks in the high refractive index encapsulation layer may reduce the functionality of optical devices.

Accordingly, what is needed in the art are optical devices with an amorphous or substantially amorphous encapsulation layer and methods of forming optical devices with the amorphous or substantially amorphous encapsulation layer.

SUMMARY

In one embodiment, a device is provided. The device includes a plurality of optical device structures disposed on a surface of a substrate. The plurality of optical device structures include a nanoparticle imprint material. The plurality of optical device structures further include an encapsulation layer disposed over at least a top surface and one sidewall of each optical device structure of the plurality of optical device structures. The encapsulation layer is amorphous or substantially amorphous. The encapsulation layer includes a niobium oxide. The niobium oxide is selected from the group consisting of niobium monoxide (NbO), niobium dioxide (NbO2), niobium pentoxide (Nb2O5), Nb12O29, Nb47O116, or Nb3n+1O8n−2, where n is 5 to 8.

In another embodiment, a device is provided. The device includes a plurality of optical device structures disposed on a substrate. The plurality of optical device structures include a nanoparticle imprint material. The plurality of optical device structures further include a buffer layer disposed over a top surface and at least one sidewall of each optical device structure of the plurality of optical device structures. The plurality of optical device structures further include an encapsulation layer disposed over the buffer layer. The encapsulation layer includes materials having a refractive index greater than or equal to 2.0.

In yet another embodiment, a method is provided. The method includes imprinting a stamp into a nanoparticle imprint material disposed on a surface of a substrate to form a plurality of optical device structures. The method further includes subjecting the nanoparticle imprint material to a cure process. The method further includes releasing the stamp from the nanoparticle imprint material. The method further includes disposing an encapsulation layer to be conformal over at least a top surface and one sidewall of each optical device structure of the plurality of optical device structures. The encapsulation layer is amorphous or substantially amorphous. The encapsulation layer includes a niobium oxide. The niobium oxide is selected from the group consisting of niobium monoxide (NbO), niobium dioxide (NbO2), niobium pentoxide (Nb2O5), Nb12O29, Nb47O116, or Nb3n+1O8n−2, where n is 5 to 8.

DETAILED DESCRIPTION

Embodiments of the present disclosure generally relate to optical devices for augmented, virtual, and mixed reality. More specifically, embodiments described herein provide for optical devices with an amorphous or substantially amorphous encapsulation layer and methods of forming optical devices with the amorphous or substantially amorphous encapsulation layer. In one embodiment, a device is provided. The device includes a plurality of optical device structures disposed on a surface of a substrate. The plurality of optical device structures include a nanoparticle imprint material. The plurality of optical device structures further include an encapsulation layer disposed over at least a top surface and one sidewall of each optical device structure of the plurality of optical device structures. The encapsulation layer is amorphous or substantially amorphous. The encapsulation layer includes a niobium oxide. The niobium oxide is selected from the group consisting of niobium monoxide (NbO), niobium dioxide (NbO2), niobium pentoxide (Nb2O5), Nb12O29, Nb47O116, or Nb3n+1O8n−2, where n is 5 to 8.

FIG. 1Ais a schematic, top view of an optical device100A.FIG. 1Bis a schematic, top view of an optical device100B. It is to be understood that the optical devices100A and100B described below are exemplary optical devices. In one embodiment, which can be combined with other embodiments described herein, the optical device100A is a waveguide combiner, such as an augmented reality waveguide combiner. In another embodiment, which can be combined with other embodiments described herein, the optical device100B is a flat optical device, such as a metasurface.

The optical devices100A and100B include a plurality of optical device structures102disposed on a surface103of a substrate101. The optical device structures102may be nanostructures having sub-micron dimensions, e.g., nano-sized dimensions. In one embodiment, which can be combined with other embodiments described herein, regions of the optical device structures102correspond to one or more gratings104, such as a first grating104a,a second grating104b,and a third grating104c.In one embodiment, which can be combined with other embodiments described herein, the optical device100A is a waveguide combiner that includes at least the first grating104acorresponding to an input coupling grating and the third grating104ccorresponding to an output coupling grating. The waveguide combiner according to the embodiment, which can be combined with other embodiments described herein, includes the second grating104bcorresponding to an intermediate grating. WhileFIG. 1Bdepicts the optical device structures102as having square or rectangular shaped cross-sections, the cross-sections of the optical device structures102may have other shapes including, but not limited to, circular, triangular, elliptical, regular polygonal, irregular polygonal, and/or irregular shaped cross-sections. In some embodiments, which can be combined with other embodiments described herein, the cross-sections of the optical device structures102on a single optical device100B are different.

The substrate101may be formed from any suitable material, provided that the substrate101can adequately transmit light in a desired wavelength or wavelength range and can serve as an adequate support for the optical device100A and the optical device100B, described herein. In some embodiments, which can be combined with other embodiments described herein, the material of the substrate101has a refractive index that is relatively low, as compared to the refractive index of the plurality of optical device structures102. Substrate selection may include substrates of any suitable material, including, but not limited to, amorphous dielectrics, non-amorphous dielectrics, crystalline dielectrics, silicon oxide, polymers, and combinations thereof. In some embodiments, which may be combined with other embodiments described herein, the substrate101includes a transparent material. In one example, the substrate101includes silicon (Si), silicon dioxide (SiO2), germanium (Ge), silicon germanium (SiGe), InP, GaAs, GaN, fused silica, quartz, sapphire, and high-index transparent materials such as high-refractive-index glass.

FIGS. 2A-2Dare schematic, cross-sectional views of a portion of an optical device taken along section line1-1ofFIG. 1AorFIG. 1B. In one embodiment, which can be combined with other embodiments described herein, the plurality of optical device structures102correspond to the first grating104a,the second grating104b,or the third grating104cof the optical device100A. The plurality of optical device structures102are disposed on the surface103of the substrate101. Each optical device structure102of the plurality of optical device structures102has an optical device structure width202. In one embodiment, which can be combined with other embodiments described herein, at least one optical device structure width202may be different from another optical device structure width202. In another embodiment, which can be combined with other embodiments described herein, each optical device structure width202of the plurality of optical device structures102is substantially equal to each other optical device structure width202.

Each optical device structure102of the plurality of optical device structures102has a depth204. In one embodiment, which can be combined with other embodiments described herein, at least one depth204of the plurality of optical device structures102is different that the depth204of the other optical device structures102. In another embodiment, which can be combined with other embodiments described herein, each depth204of the plurality of optical device structures102is substantially equal to the adjacent optical device structures102.

The plurality of optical device structures102are initially formed from a malleable nanoparticle imprint material210A, as shown inFIGS. 5A and 5B. The malleable nanoparticle imprint material210A is cured such that the plurality of optical device structures102consist of an unmalleable nanoparticle imprint material210B. The plurality of optical device structures102are crystalline or nano-crystalline due to the unmalleable nanoparticle imprint material110B. In some embodiments, which can be combined with other embodiments described herein, the plurality of optical devices102formed from the unmalleable nanoparticle imprint material210B have a refractive index greater than about 1.5. In one embodiment, which can be combined with other embodiments described herein, the plurality of optical devices102formed from the unmalleable nanoparticle imprint material210B have a refractive index between about 1.8 and about 2.1. In another embodiment, which can be combined with other embodiments described herein, the plurality of optical devices102formed from the unmalleable nanoparticle imprint material210B have a refractive index between about 3.5 and about 4.0.

In one embodiment, which can be combined with other embodiments described herein, the malleable nanoparticle imprint material210A and the unmalleable nanoparticle imprint material210B includes, but are not limited to, one or more of spin on glass (SOG), flowable SOG, organic, inorganic, hybrid organic, and inorganic nanoimprintable materials. The malleable nanoparticle imprint material210A and the unmalleable nanoparticle imprint material210B may include silicon oxycarbide (SiOC), titanium dioxide (TiO2), silicon dioxide (SiO2), vanadium (IV) oxide (VO2), aluminum oxide (Al2O3), indium tin oxide (ITO), zinc oxide (ZnO), tantalum pentoxide (Ta2O5), silicon nitride (Si3N4), titanium nitride (TiN), or zirconium dioxide (ZrO2) containing materials.

The plurality of optical device structures102are formed at a device angle ϑ. The device angle ϑ is the angle between the surface103of the substrate101and the sidewall208of the optical device structure102. As shown inFIGS. 2A and 2C, the plurality of optical devices102are vertical, i.e., the device angle ϑ is 90 degrees. As shown inFIGS. 2B and 2D, the plurality of optical devices102are angled relative to the surface103of the substrate101. In one embodiment, which can be combined with other embodiments described herein, each respective device angle ϑ for each optical device structure102is substantially equal. In another embodiment, which can be combined with other embodiments described herein, at least one respective device angle ϑ of the plurality of optical device structures102is different than another device angle ϑ of the plurality of optical device structures102.

As shown inFIGS. 2A and 2B, an encapsulation layer214including niobium oxide is disposed over the plurality of optical device structures102and the surface103of the substrate101. The niobium oxide is selected from the group consisting of niobium monoxide (NbO), niobium dioxide (NbO2), niobium pentoxide (Nb2O5), Nb12O29, Nb47O116, or Nb3n+1O8n−2, where n is 5 to 8. Examples of Nb3n+1O8n−2include Nb8O19and Nb16O38. In one embodiment, which can be combined with other embodiments described herein, the encapsulation layer214including the niobium oxide has a refractive index between about 2.1 and about 2.5. In one embodiment, which can be combined with other embodiments described herein, the encapsulation layer214is deposited such that the encapsulation layer214is disposed over at least a top surface206and one sidewall208of each optical device structure102of the plurality of optical device structures102. In another embodiment, which can be combined with other embodiments described herein, the encapsulation layer214is disposed over the top surface206and both sidewalls208of each optical device structure102of the plurality of optical device structures102and over the surface103of the substrate101. The encapsulation layer214may be disposed using a liquid material pour 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 FCVD process, a PECVD process, or an ALD process.

As shown inFIGS. 2C and 2D, an encapsulation layer215includes one or more materials with a refractive index greater than or equal to 2.0, i.e., a high refractive index. The materials can include one or more of silicon oxycarbide, titanium oxide, silicon oxide, vanadium oxide, aluminum oxide, aluminum-doped zinc oxide, indium tin oxide, tin dioxide, zinc oxide, tantalum pentoxide, silicon nitride, silicon oxynitride, zirconium oxide, niobium oxide, cadmium stannate, or silicon carbon-nitride containing materials. The encapsulation layer215is deposited over a buffer layer212. In one embodiment, which can be combined with other embodiments described herein, the buffer layer212is deposited over the top surface206and at least one sidewall208of each optical devices structure102of the plurality of optical device structures102. In another embodiment, which can be combined with other embodiments described herein, the encapsulation layer214is disposed over the top surface206and both sidewalls208of each optical device structure102of the plurality of optical device structures102and over the surface103of the substrate101.

The buffer layer212may be disposed using a liquid material pour 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 FCVD process, a PECVD process, or an ALD process. The buffer layer212includes, but is not limited to, at least one or more of silicon oxycarbide, titanium oxide, silicon oxide, vanadium oxide, aluminum oxide, aluminum-doped zinc oxide, indium tin oxide, tin dioxide, zinc oxide, tantalum pentoxide, silicon nitride, silicon oxynitride, zirconium oxide, niobium oxide, cadmium stannate, or silicon carbon-nitride containing materials or combinations thereof.

In one embodiment, which can be combined with other embodiments described herein, the refractive index of either the buffer layer212or the encapsulation layer215with a titanium oxide material is between about 2.3 and about 2.7. In another embodiment, which can be combined with other embodiments described herein, the refractive index of either the buffer layer212or the encapsulation layer215with a tantalum pentoxide material is between about 2.0 and about 2.2. In yet another embodiment, which can be combined with other embodiments described herein, the refractive index of either the buffer layer212or the encapsulation layer215with a zirconium oxide material is between about 2.0 and about 2.2.

The refractive index of the buffer layer is greater than or equal to about 1.8. In one embodiment, which can be combined with other embodiments described herein, the buffer layer212and the plurality of optical device structures102have the same refractive index. In another embodiment, which can be combined with other embodiments described herein, the buffer layer212and the encapsulation layer215have the same refractive index. In yet another embodiment, which can be combined with other embodiments described herein, the refractive index of the buffer layer212is between the refractive index of the plurality of optical device structures102and the encapsulation layer115.

FIGS. 3Ais a cross-sectional view of an optical device structure102with the encapsulation layer215.FIG. 3Cis a cross-sectional view of a portion221of an optical device structure102with the encapsulation layer215. The encapsulation layer215includes one or more materials with a refractive index greater than or equal to 2.0 i.e., a high refractive index. The materials can include one or more of silicon oxycarbide, titanium oxide, silicon oxide, vanadium oxide, aluminum oxide, aluminum-doped zinc oxide, indium tin oxide, tin dioxide, zinc oxide, tantalum pentoxide, silicon nitride, zirconium oxide, niobium oxide, cadmium stannate, or silicon carbon-nitride containing materials.FIG. 3Bis a cross-sectional view of a portion220of an optical device structure102with the encapsulation layer214. The encapsulation layer214includes a niobium oxide. The niobium oxide selected from the group consisting of niobium monoxide (NbO), niobium dioxide (NbO2), niobium pentoxide (Nb2O5), Nb12O29, Nb47O116, or Nb3n+1O8n−2, where n is 5 to 8. Examples of Nb3n+1O8n−2include Nb8O19and Nb16O38.

Each optical device structure102of the plurality of optical device structures102includes the unmalleable nanoparticle imprint material210B. The unmalleable nanoparticle imprint material210B has a plurality of nanoparticles302. The plurality of nanoparticles302are crystals or nano-crystals that can lead to crystalline formations in subsequent depositions over the plurality of optical devices102. Adjacent nanoparticles302of the plurality of nanoparticles302define a plurality of grain boundaries304. A grain boundary304of the plurality of grain boundaries304is present at any interface between adjacent nanoparticles302.

As shown inFIG. 3A, the encapsulation layer215includes a titanium oxide material. The encapsulation layer215includes a plurality of cracks306. The cracks306are induced by the adjacent grain boundaries304in the unmalleable nanoparticle imprint material210B. The plurality of grain boundaries304propagate into the encapsulation layer215to form the cracks306when the encapsulation layer215is non-amorphous. The cracks306lead to degradation of the underlying plurality of optical device structures102and reduce functionality of the optical device100A or the optical device100B.

As shown inFIG. 3B, the encapsulation layer214including the niobium oxide is lacking or substantially lacking cracks306. In one embodiment, which can be combined with other embodiments described herein, the encapsulation layer214including the niobium oxide has a refractive index between about 2.1 and about 2.5. The niobium oxide is amorphous or substantially amorphous such that the plurality of grain boundaries304are not induced in the encapsulation layer214. The encapsulation layer214including the niobium oxide provides a higher encapsulation quality as the amorphous or substantially amorphous properties lead to a smoother encapsulation layer214and provide less variation in the optical properties of the underlying optical device structures102. Additionally, the encapsulation layer214including the niobium oxide is substantially less sensitive to temperature than the encapsulation layer215. Therefore, the optical devices100A and100B with the encapsulation layer214will lead to higher throughput.

As shown inFIG. 3C, the encapsulation layer215includes one or more materials with a refractive index greater than or equal to 2.0, i.e., a high refractive index. The encapsulation layer215is disposed over the buffer layer212. The buffer layer212provides a barrier between the plurality of nanoparticles302and the encapsulation layer215such that cracks306do not form in the encapsulation layer215.

FIG. 4is a flow diagram of a method400for forming the optical devices100A and100B, as shown inFIGS. 5A-5C.FIGS. 5A-5Dare schematic, cross-sectional views of a portion105of the optical device100A or the optical device100B. At operation401, as shown inFIG. 5A, a malleable nanoparticle imprint material210A is deposited on a surface103of a substrate101. The malleable nanoparticle imprint material210A is deposited using a deposition process. The deposition process may include a spin on process, liquid material pour casting 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 FCVD process, or an ALD process. In one embodiment, which can be combined with other embodiments described herein, the malleable nanoparticle imprint material210A is deposited with a spin on process.

In one embodiment, which can be combined with other embodiments described herein, the malleable nanoparticle imprint material210A includes, but is not limited to, one or more of spin on glass (SOG), flowable SOG, organic, inorganic, hybrid organic, and inorganic nanoimprintable materials. The malleable nanoparticle imprint material210A may include silicon oxycarbide (SiOC), titanium dioxide (TiO2), silicon dioxide (SiO2), vanadium (IV) oxide (VO2), aluminum oxide (Al2O3), indium tin oxide (ITO), zinc oxide (ZnO), tantalum pentoxide (Ta2O5), silicon nitride (Si3N4), titanium nitride (TiN), or zirconium dioxide (ZrO2) containing materials.

At operation402, as shown inFIG. 5B, a stamp502is imprinted into the malleable nanoparticle resist material210A. In one embodiment, the malleable nanoparticle imprint material210A is heated to a preheat temperature before the stamp502is imprinted. The stamp502has a plurality of inverse structures504. The plurality of inverse structures504are imprinted into the malleable nanoparticle imprint material210A to form a plurality of optical device structures102. The plurality of optical device structures102have a device angle ϑ. The device angle ϑ is the angle between the surface103of the substrate101and the sidewall208of the optical device structure102. The stamp502is molded such that the plurality of inverse structures504are at a stamp angle φ. The stamp angle φ is the angle between a plane506parallel with the surface103and a sidewall508of the plurality of inverse structures504. In one embodiment, which can be combined with other embodiments described herein, the stamp angle φ will correspond to the device angle ϑ when the stamp502is imprinted into the nanoparticle resist material210A.

The stamp502is molded from a master and may be made from a semi-transparent material, such as fused silica or polydimethylsiloxane (PDMS) material, or a transparent material, such as a glass material or a plastic material, to allow the nanoim print resist to be cured by exposure to electromagnetic radiation, such as infrared (IR) radiation or ultraviolet (UV) radiation. In one embodiment, the stamp502may be coated with a mono-layer of anti-stick surface treatment coating, such as a fluorinated coating, so the stamp502can be mechanically removed by a machine tool or by hand peeling. AlthoughFIGS. 5B and 5Cshow the plurality of inverse structures504of the stamp502and the plurality of optical device structures102as being at an angle relative to the surface103of the substrate101, the plurality of inverse structures504and plurality of optical device structures102may be vertical i.e., the stamp angle φ and the device angle ϑ are 90°, as shown inFIGS. 2A and 2C.

At operation403, the malleable nanoparticle imprint material210A is subjected to a cure process. In one embodiment, the malleable nanoparticle imprint material210A is subjected to the cure process to form the nonmalleable nanoparticle imprint material210B. The cure process includes exposing the nanoparticle imprint material210to electromagnetic radiation, such as infrared (IR) radiation or ultraviolet (UV) radiation. The unmalleable nanoparticle imprint material210B is rigid such that the unmalleable nanoparticle imprint material210B is crystalline or nano-crystalline.

At operation404, as shown inFIG. 5C, the stamp502is released. In one embodiment, which can be combined with other embodiments described herein, the stamp502is peeled at the release angle relative to the surface103of the substrate101. In another embodiment, which can be combined with other embodiments described herein, the stamp502is mechanically peeled by a machine tool at the release angle. In yet another embodiment, the stamp502is peeled by hand at the release angle. The release angle is about 0° to about 180°. In another embodiment, which can be combined with other embodiments described herein, the unmalleable nanoparticle imprint material210B is subjected to an anneal process after the operation404. The anneal process includes exposing the nanoparticle imprint material210to electromagnetic radiation, such as infrared (IR) radiation or ultraviolet (UV) radiation, until the unmalleable nanoparticle imprint material210B reaches an anneal state.

At operation405, as shown inFIG. 2B, an encapsulation layer214is disposed. The encapsulation layer214is disposed over the plurality of optical device structures102. The encapsulation layer214is disposed over a top surface206and at least one sidewall208of each optical device structure102of the plurality of optical device structures102. The encapsulation layer214is disposed using a liquid material pour 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 FCVD process, a PECVD process, or an ALD process. The encapsulation layer214includes a niobium oxide. The niobium oxide selected from the group consisting of niobium monoxide (NbO), niobium dioxide (NbO2), niobium pentoxide (Nb2O5), Nb12O29, Nb47O116, or Nb3n+1O8n−2, where n is 5 to 8. Examples of Nb3n+1O8n−2include Nb8O19and Nb16O38. In one embodiment, which can be combined with other embodiments described herein, the encapsulation layer214including the niobium oxide has a refractive index between about 2.1 and about 2.5.

In one embodiment, which can be combined with other embodiments described herein, the encapsulation layer214including the niobium oxide will be deposited onto the unmalleable nanoparticle imprint material210B. The encapsulation layer214is amorphous or substantially amorphous such that the plurality of grain boundaries304in the unmalleable nanoparticle imprint material210B do not propagate to the encapsulation layer114.

FIG. 6is a flow diagram of a method600for forming the optical devices100A and100B, as shown inFIGS. 7A-7D.FIGS. 7A-7Dare schematic, cross-sectional views of a portion105of the optical device100A or the optical device100B. At operation601, as shown inFIG. 7A, a malleable nanoparticle imprint material210A is deposited on a surface103of a substrate101.

At operation602, as shown inFIG. 7B, a stamp702is imprinted into the malleable nanoparticle resist material210A. In one embodiment, the malleable nanoparticle imprint material210A is heated to a preheat temperature before the stamp502is imprinted. The stamp702has a plurality of inverse structures704. The plurality of inverse structures704are imprinted into the malleable nanoparticle imprint material210A to form a plurality of optical device structures102. The plurality of optical device structures102have a device angle ϑ. The device angle ϑ is the angle between the surface103of the substrate101and the sidewall208of the optical device structure102. The stamp702is molded such that the plurality of inverse structures704are at a stamp angle φ. The stamp angle φ is the angle between a plane706parallel with the surface103and a sidewall708of the plurality of inverse structures704. In one embodiment, which can be combined with other embodiments described herein, the stamp angle φ will correspond to the device angle ϑ when the stamp702is imprinted into the nanoparticle resist material210A.

The stamp702is molded from a master and may be made from a semi-transparent material, such as fused silica or polydimethylsiloxane (PDMS) material, or a transparent material, such as a glass material or a plastic material, to allow the nanoim print resist to be cured by exposure to electromagnetic radiation, such as infrared (IR) radiation or ultraviolet (UV) radiation. In one embodiment, the stamp702may be coated with a mono-layer of anti-stick surface treatment coating, such as a fluorinated coating, so the stamp702can be mechanically removed by a machine tool or by hand peeling. AlthoughFIGS. 7B and 7Cshow the plurality of inverse structures704of the stamp702and the plurality of optical device structures102as being at an angle relative to the surface103of the substrate101, the plurality of inverse structures704and plurality of optical device structures102may be vertical i.e., the stamp angle φ and the device angle ϑ are 90°, as shown inFIGS. 2A and 2C.

At operation603, the malleable nanoparticle imprint material210A is subjected to a cure process. In one embodiment, the malleable nanoparticle imprint material210A is subjected to the cure process to form the nonmalleable nanoparticle imprint material210B. The cure process includes exposing the nanoparticle imprint material210to electromagnetic radiation, such as infrared (IR) radiation or ultraviolet (UV) radiation. The unmalleable nanoparticle imprint material210B is rigid such that the unmalleable nanoparticle imprint material210B is crystalline or nano-crystalline.

At operation604, as shown inFIG. 7C, the stamp502is released. In one embodiment, which can be combined with other embodiments described herein, the stamp502is peeled at the release angle relative to the surface103of the substrate101. In another embodiment, which can be combined with other embodiments described herein, the stamp502is mechanically peeled by a machine tool at the release angle. In yet another embodiment, the stamp502is peeled by hand at the release angle. The release angle is about 0° to about 180°. In another embodiment, which can be combined with other embodiments described herein, the unmalleable nanoparticle imprint material210B is subjected to an anneal process after the operation404. The anneal process includes exposing the nanoparticle imprint material210to electromagnetic radiation, such as infrared (IR) radiation or ultraviolet (UV) radiation, until the unmalleable nanoparticle imprint material210B reaches an anneal state.

At operation605, a buffer layer212is disposed. The buffer layer212is disposed over the plurality of optical device structures102. The buffer layer212is deposited over the top surface206and at least one sidewall208of each optical device structure102of the plurality of optical device structures102. The buffer layer is deposited using a liquid material pour 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 FCVD process, a PECVD process, or an ALD process.

At operation606, as shown inFIG. 2D, the encapsulation layer215is disposed. The encapsulation layer215is disposed over the buffer layer212. The encapsulation layer215includes a high-refractive index material such as titanium oxide (TiO) or zirconium oxide (ZrO) materials. The buffer layer212provides a barrier between the unmalleable nanoparticle imprint material210B and the encapsulation layer215. Therefore, the encapsulation layer215will be absent or substantially absent of the plurality of cracks306.

In one embodiment, which can be combined with other embodiments described herein, the encapsulation layer214including the niobium oxide will be deposited onto the unmalleable nanoparticle imprint material210B. The encapsulation layer214will be absent or substantially absent of the plurality of cracks306. The encapsulation layer214is amorphous or substantially amorphous such that the plurality of grain boundaries304in the unmalleable nanoparticle imprint material210B do not propagate to the encapsulation layer114.

In summation, optical devices with an amorphous or substantially amorphous encapsulation layer and methods of forming optical devices with the amorphous or substantially amorphous encapsulation layer are described herein. The encapsulation layer including the niobium oxide is deposited over the plurality of optical device structures. The encapsulation layer including the niobium oxide, as described herein, is amorphous or substantially amorphous such that the encapsulation layer is less prone to forming cracks in the encapsulation layer. Additionally, a buffer layer can be disposed over the plurality of optical device structures to provide a barrier between the optical device structures and an encapsulation layer to prevent cracks in the encapsulation layer. Therefore, the encapsulation quality of the optical device is improved due to the amorphous encapsulation layer.

While the foregoing is directed to examples of the present disclosure, other and further examples of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.