Conformal sealing of low index film at edge of coating

Abstract

The present disclosure generally provides waveguide combiners for augmented reality applications and methods thereof. The waveguide combiners include a substrate. A coating layer having a refractive index of about 1.03 to 1.3 is disposed over the substrate. One or more seal structures having refractive indices of about 1.15 to 2.0 are disposed adjacent to the coating layer. An edge black material is disposed over the edges of the substrate, the coating layer, and the seal structures. The edge black material functions to absorb stray light and improve image contrast. The coating layer prevents light leakage, while the seal structures protect the coating layer from moisture and debris.

Description

CONFORMAL SEALING OF LOW INDEX FILM AT EDGE OF COATING BACKGROUNDField

[0001] Embodiments of the present disclosure generally relate to waveguides. More specifically, embodiments described herein relate to a sealing structure for low index films at the edge of a coating of a waveguide.Description of the Related Art

[0002] Virtual reality (VR) 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.

[0003] Augmented reality (AR), 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 for display and 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 enhances or augments the environment that the user experiences. As an emerging technology, there are many challenges and design constraints with augmented reality.

[0004] VR and AR lenses are diced from a wafer using two methods: filamentation dicing and water jet guided laser dicing. Filamentation dicing is a laser cutting technique that uses short-pulse laser processing to cut brittle materials like glass. Waterjet guided laser dicing uses water as a guide to the laser and thus using solvent stripping at the end of the dicing procedure.

[0005] While low index films are beneficial for monolithic design of a waveguide in the field of augmented reality, these low index films are fragile and have challenges tolerating the harsh processing conditions unless the low index film is sealed. Low index films can be porous, such that water and solvent stripping can weaken the film. Filamentation dicing does not involve water, therefore there is no need for a protectivecoating and thus no need for solvent stripping. While the filamentation dicing does not require a protective coating, certain substrates can only be diced using waterjet guided laser. However, conventional sealing still suffers from drawbacks.

[0006] Therefore, there is a need for improved sealing methods.SUMMARY

[0007] In one embodiment, a device is disclosed. The device includes a substrate, a coating disposed over a substrate and having a first refractive index from about 1.03 to about 1.3, where an edge portion of the substrate is exposed by the coating, a first seal disposed over the coating and having a second refractive index of about 1.15 to about 2.0, a second seal disposed over the first seal, and edge of the first seal, an edge of the coating, and the edge portion of the substrate and having a third refractive index of about 1.15 to about 2.0, and an edge black disposed over an edge portion of the second seal, an edge of the second seal, and an edge of the substrate.

[0008] In another embodiment, an augmented reality waveguide is disclosed. The augmented reality waveguide includes a substrate, at least one grating disposed over the substrate, an edge coating material disposed over an edge portion of the substrate, and a layer stack disposed over the substrate between the at least one grating and the edge portion of the substate, the layer stack including a coating having a first refractive index from about 1.03 to about 1.3, and a first seal having a second refractive index of about 1.15 to about 2.0, where the edge coating material is disposed on the edge portion of the substrate, on sidewalls of the coating and the first seal adjacent to the edge portion, and over an upper surface of the layer stack.

[0009] In yet another embodiment, a device is disclosed. The device includes a substrate, a coating disposed over a substrate and having a first refractive index from about 1.03 to about 1.3, where an edge portion of the substrate is exposed by the coating, a first seal disposed over the coating and having a second refractive index of about 1.15 to about 2.0, and an edge black disposed over an edge portion of the first seal, an edge of the first seal, an edge of the coating, the edge portion of the substrate, and an edge of the substrate.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of scope, as the disclosure may admit to other equally effective embodiments.

[0011] Figure 1 is a front view of a waveguide combiner, according to embodiments.

[0012] Figure 2A is an edge blacked waveguide combiner, according to embodiments.

[0013] Figure 2B is a double sealed edge blacked waveguide combiner, according to embodiments.

[0014] Figure 2C is an extended edge blacked waveguide combiner, according to embodiments.

[0015] Figure 2D and Figure 2E illustrate embodiments of the edge blacked waveguide combiner, according to embodiments.

[0016] Figure 3 is a flow chart of a method of forming an edge blacked waveguide combiner, according to embodiments.

[0017] Figures 4A-4G are cross-sectional view of the edge blacked waveguide combiner during the method of Figure 3, according to embodiments.

[0018] Figure 5 is a flow chart of a method of forming a double sealed edge blacked waveguide combiner, according to embodiments.

[0019] Figures 6A-6H are cross-sectional view of the double sealed edge blacked waveguide combiner during the method of Figure 5, according to embodiments.

[0020] Figure 7 is a flow chart of a method of forming an extended edge blacked waveguide combiner, according to embodiments.

[0021] Figures 8A-8G are cross-sectional view of the extended edge blacked waveguide combiner during the method of Figure 7, according to embodiments.

[0022] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.DETAILED DESCRIPTION

[0023] Embodiments of the present disclosure generally relate to waveguides. More specifically, embodiments described herein relate to a sealing structure for low index films at the edge of a coating of a waveguide.

[0024] Figure 1 is a front view of a waveguide combiner 100. It is to be understood that the waveguide combiner 100 described below is an exemplary waveguide combiner, and other shapes are contemplated. The waveguide combiner 100 includes a substrate 101 and a plurality of optical devices 104. The substrate 101 includes a silicon carbide (SiC) or a lithium niobate (LiNbOs). The plurality of optical devices 104 include an input coupling region 104A, a waveguide region 104B, and an output coupling region 104C. The input coupling region 104A, the waveguide region 104B, and the output coupling region 104C are defined by a plurality of gratings 106.

[0025] The input coupling region 104A receives incident beams of light (e.g., a light image) having an intensity from a display (e.g., a micro-display). Each grating of the plurality of gratings 106 splits the incident beams into a plurality of modes. Zero-order mode (TO) beams are refracted back or lost in the waveguide combiner 100. Positive first order mode (T1) beams undergo total-internal-reflection (TIR) through the waveguide combiner 100 across the waveguide region 104B to the output coupling region 104C and output for display. Negative first-order mode (T-1) beams propagate in the waveguide combiner 100 a direction opposite the T1 beams. Among the diffracted orders, only the T 1 beams output for display through output coupling region 104C, while other modes are lost due to different directionality. Therefore, it is beneficial to increase T1 beam internal loss (e.g., increase T1 absorption) within the substrate in order to increase image contrast.

[0026] Figure 2A is an edge blacked waveguide combiner 200A. The edge blacked waveguide combiner 200A may be a portion of the waveguide combiner 100 at cut line A-A. The edge blacked waveguide combiner 200A includes a substrate 201, a layer stack 255, and an edge coating material (e.g., an edge black 214). The layer stack 255 comprising a coating 210 and a first seal 212.

[0027] The layer stack 255 is disposed over the substrate 201 between the plurality of gratings 106 and an edge portion 220 of the substrate 201. The coating 210 of the layer stack 255 is disposed over the substrate 201 using spin coating, inkjet printing, screen printing, physical vapor deposition (PVD), chemical vapor deposition (CVD), or atomic layer deposition (ALD). The edge portion 220 of the substrate 201 is exposed by the coating 210. The edge portion 220 of the substrate 201 is a portion of the substrate 201 adjacent to an edge 218 (e.g., a side or sidewall) of the substrate 201. The edge portion 220 has a radial distance D1 from an edge 217 of the coating 210 to the edge 218 of the substrate 201 of about 15 pm to about 3 mm. The coating 210 has a thickness of about 0.8 pm to about 1.2 pm. The coating 210 is a porous silica or fluorinated polymers. The coating 210 has a refractive index (Rl) from about 1.03 to about 1.3, for example, the porous silica may have a Rl of less than 1.3, such as a Rl of less than 1.2. The coating 210 prevents or reduces light leakage by trapping the light that is propagating through the waveguide within the waveguide.

[0028] The first seal 212 is disposed over the coating 210 using spin coating, inkjet printing, screen printing, PVD, CVD, or ALD. The first seal 212 has a thickness of about 2 nm to about 100 pm, such as about 1 pm to 50 pm, such as about 50 nm to about 500 nm, such as about 100 nm to about 300 nm. The first seal 212 includes a metal oxide or an organic material. The metal oxide includes silicon oxide (SiC>2), silicon oxynitride (SiON), aluminum oxide (AIO), silicon nitride (SiN) , or similar metal oxides. The organic material includes polymer materials, such as polydimethylsiloxane (PDMS), polyacrylate, epoxy, polyimide, polystyrene, and combinations thereof. The first seal 212 has a Rl from about 1.15 to about 2.0. The first seal 212 provides a protective seal for the coating 210 to prevent moisture and debris from contaminating the coating 210.

[0029] The edge black 214 is disposed over an edge portion 215 of the first seal 212 (e.g., an upper surface of the layer stack 255), the edge 216 of the first seal 212,an edge 217 of the coating 210, and an edge portion 220 of the substrate 201. The edge portion 215 of the first seal 212 is a portion of the first seal 212 adjacent to the edge 216 (e.g., a side or sidewall) of the first seal 212. The edge portion 215 has a radial distance D2 of about 15 pm to about 3 mm. The edge black 214 has a thickness of about 100 nm to about 500 nm. The edge black 214 includes an organic carbon black, a UV curable or thermally curable liquid material, such as polydimethylsiloxane (PDMS), polyacrylate, epoxy, polyimide, polystyrene, and combinations thereof, combination thereof. The edge black 214 absorbs light at the edges of the edge blacked waveguide combiner 200A to improve image contrast of the edge blacked waveguide combiner 200A. Further, the edge black 214 provides a barrier layer for the coating 210 to prevent moisture and debris from contaminating the coating 210.

[0030] The edge black 214 is an optically absorbent composition may have a refractive index that is substantially similar to the refractive index of the waveguide (e.g., substrate 201). In some embodiments, which may be combined with other embodiments described herein, the substrate 201 has a substrate refractive index greater than 1.4. In some embodiments, the edge black 214 has a refractive index greater than 1 .5. For example, the edge black 214 may have a refractive index of 1.7 or greater, 1.9 or greater, or 2.1 or greater. In some embodiments, the edge black 214 has a refractive index from about 1.7 to about 2.1, from about 1.6 to about 2.0, from about 1.5 to about 1.9, or from about 1.7 to about 1.9. In some embodiments, the refractive index of the edge black 214 is less than about 0.1 % to about 50% of the refractive index of the substrate 201. In one or more embodiments, the edge black 214 has a refractive index of 2.0 or greater.

[0031] In some embodiments, the edge black 214 may be conformal to the edge portion 215 of the first seal 212, the edge 216 of the first seal 212, an edge 217 of the coating 210, and an edge portion 220 of the substrate 201. In other embodiments, the edge black 214 may have a planar upper surface, e.g., the thickness of the edge black 214 disposed over the edge portion 220 of the substrate 201 is greater than the thickness of the edge black 214 disposed over the edge portion 215 of the first seal 212.

[0032] Figure 2B is a double sealed edge blacked waveguide combiner 200B. The double sealed edge blacked waveguide combiner 200B may be a portion of thewaveguide combiner 100 at cut line A-A. The double sealed edge blacked waveguide combiner 200B includes a substrate 201, a layer stack 255, and an edge coating material (e.g., an edge black 214). The layer stack 255 is disposed over the substrate 201 between the plurality of gratings 106 and an edge portion 220 of the substrate 201. The layer stack 255 comprises a coating 210, a first seal 212, and a second seal 213. The layer stack 255 is disposed over the substrate 201 such that the coating 210 is disposed over the substrate 201 and the first seal 212 is disposed over the coating 210. An edge portion 220 of the substrate 201 is exposed by the coating 210.

[0033] The second seal 213 is disposed over the first seal 212, an edge 216 of the first seal 212, an edge 217 of the coating 210, and an edge portion 220 of the substrate 201. The second seal 213 may be deposited using atomic layer deposition (ALD) or chemical vapor deposition (CVD) to enable a more conformal deposition. The second seal 213 has a thickness of about 2 nm to about 100 pm. The second seal 213 includes a metal oxide or an organic material. The metal oxide includes silicon oxide (SiC>2), silicon oxynitride (SiON), aluminum oxide (AIO), silicon nitride (SiN), or similar metal oxides. The organic material includes polydimethylsiloxane (PDMS), polyacrylate, epoxy, polyimide, polystyrene, and combinations thereof. The second seal 213 has a second seal Rl from about 1.15 to about 2.0. In some embodiments, the second seal Rl is the same as the first seal Rl. In other embodiments, the second seal Rl is different from the first seal Rl. In some embodiments, the second seal 213 may be conformal to the edge 216 of the first seal 212, an edge 217 of the coating 210, and an edge portion 220 of the substrate 201. In other embodiments, the second seal 213 may have a planar upper surface, e.g., the thickness of the second seal 213 disposed over the edge portion 220 of the substrate 201 is greater than the thickness of the second seal 213 disposed over the first seal 212.

[0034] The edge black 214 is disposed over an edge portion 219 of the second seal 213 (e.g., an upper surface of the layer stack 255), the edge 221 of the second seal 213, and an edge 218 of the substrate 201 . The edge portion 219 of the second seal 213 is a portion of the second seal 213 adjacent to the edge 221 (e.g., a side or sidewall) of the second seal 213. The edge portion 219 has a radial distance D3 of about 15 pm to about 3 mm. The edge portion 219 includes a vertical segment 222 and a horizontal segment 223. The vertical segment 222 is disposed over the edge223 is disposed over the edge portion 220 of the substrate 201. The edge black is deposited via screen-printing, needle dispensing, inkjet, or single nozzle jetting. The edge black 214 absorbs light at the edges of the double sealed edge blacked waveguide combiner 200B to improve image contrast of the double sealed edge blacked waveguide combiner 200B. Further, the edge black 214 provides a barrier layer for the coating 210 to prevent moisture and debris from contaminating the coating 210. In some embodiments, the edge black 214 may be conformal to the edge portion 215 of the second seal 213, the edge 221 of the second seal, and the edge 218 of the substrate 201. In other embodiments, the edge black 214 may have a planar upper surface, e.g., the thickness of the edge black 214 disposed over the edge 218 of the substrate 201 (e.g., the thickness of the edge black 214 measured from the bottom surface of the substrate 201 to the upper surface of the edge black 214) is greater than the thickness of the edge black 214 disposed over the edge portion 219 of the second seal 213.

[0035] Figure 2C is an extended edge blacked waveguide combiner 200C. The extended edge blacked waveguide combiner 200C may be a portion of the waveguide combiner 100 at cut line A-A. The extended edge blacked waveguide combiner 200C includes a substrate 201, a layer stack 255, and an edge coating material (e.g., an edge black 214). The layer stack 255 comprising a coating 210 and a first seal 212. The layer stack 255 is disposed over the substrate 201 between the plurality of gratings 106 and an edge portion 220 of the substrate 201.

[0036] The edge black 214 is disposed over an edge portion 215 of the first seal 212 (e.g., an upper surface of the layer stack 255), an edge 216 of the first seal 212, an edge 217 of the coating 210, an edge portion 220 of the substrate 201, and an edge 218 of the substrate 201. The edge black 214 absorbs light at the edges of the extended edge blacked waveguide combiner 200C to improve image contrast of the extended edge blacked waveguide combiner 200C. Further, the edge black 214 provides a barrier layer for the coating 210 to prevent moisture and debris from contaminating the coating 210. In some embodiments, the edge black 214 may be conformal to the edge portion 215 of the first seal 212, the edge 217 of the coating, the edge portion 220 of the substrate 201 , and the edge 218 of the substrate 201. In other embodiments, the edge black 214 may have a planar upper surface, e.g., the thickness of the edge black 214 disposed over the edge 218 of the substrate 201 (e.g. ,the thickness of the edge black 214 measured from the bottom surface of the substrate 201 to the upper surface of the edge black 214) is greater than the thickness of the edge black 214 disposed over the edge portion 215 of the first seal 212.

[0037] Figure 2D is a waveguide combiner 200D with a device layer 250. The waveguide combiner 200D may be a portion of the waveguide combiner 100 at cut line D-D. The device layer 250 is disposed over the substrate 201. A grating 204 is formed in the device layer 250. The grating 204 may be the grating 106 of the input coupling region 104A, the waveguide region 104B, or the output coupling region 104C. The device layer 250 has a refractive index of about 1.9 to about 4.0. The device layer 250 includes, but is not limited to, materials such as or containing germanium, silicon, titanium oxide, niobium oxide, silicon nitride, hafnium oxide, tantalum oxide, scandium oxide, or combinations thereof. The layer stack 255 is disposed over the device layer 250 between the plurality of gratings 106 and an edge portion 220 of the substrate 201. The layer stack 255 includes a coating 210 and a first seal 212. The coating 210 is disposed over the device layer 250. The first seal 212 is disposed over the coating 210. In the illustrated embodiment, the layer stack 255 is not disposed over the grating 204. The edge black 214 is disposed over an edge portion 215 of the first seal 212 (e.g., an upper surface of the layer stack 255), the edge 216 of the first seal 212, an edge 217 of the coating 210, an edge 256 (e.g., a side or sidewall) of the device layer 250, and an edge portion 220 of the substrate 201.

[0038] Figure 2E is a waveguide combiner 200E with a layer stack 255 disposed over a grating 204. The waveguide combiner 200D may be a portion of the waveguide combiner 100 at cut line D-D. The grating 204 is formed in a device layer 250. The grating 204 may be the grating 106 of the input coupling region 104A, the waveguide region 104B, or the output coupling region 104C. The layer stack 255 is disposed over the device layer 250 and the grating 204. In some embodiments, the layer stack 255 is disposed between a plurality of optical device structures 204A of the grating 204. In other embodiments, the layer stack 255 is not disposed between the plurality of optical device structures 204A. The edge black 214 is disposed over an edge portion 215 of the first seal 212 (e.g., an upper surface of the layer stack 255), the edge 216 of the first seal 212, an edge 217 of the coating 210, an edge 256 (e.g., a side or sidewall) of the device layer 250, and an edge portion 220 of the substrate 201.

[0039] Figure 2D and Figure 2E illustrate alternative embodiments of the edge blacked waveguide combiner 200A. Similar modifications may be made to the embodiments of the double sealed edge blacked waveguide combiner 200B and the extended edge blacked waveguide combiner 200C.

[0040] Figure 3 is a flow chart of a method 300 of forming an edge blacked waveguide combiner 200A. Figures 4A-4G are cross-sectional view of the edge blacked waveguide combiner 200A during the method 300.

[0041] At operation 301, as shown in Figure 4A, a resist 430 is disposed over a first seal 212 of a partial waveguide 400A. The first seal 212 is disposed over a coating 210. The coating 210 is disposed over a substrate 201. The first seal 212 and the coating 210 together form a layer stack 255. In some embodiments, the layer stack 255 is disposed over a device layer 250, which is disposed over the substrate 201. The resist 430 is a positive resist or a negative resist. A positive resist includes portions of the resist, which, when exposed to electromagnetic radiation, are respectively soluble to a resist developer applied to the resist after the pattern is written into the resist using the electromagnetic radiation. A negative resist includes portions of the resist, which, when exposed to radiation, will be respectively insoluble to the resist developer applied to the resist after the pattern is written into the resist using the electromagnetic radiation. The chemical composition of the resist 430 determines whether the resist 430 is a positive resist or a negative resist. The patterning is one of a photolithography, digital lithography process, or laser ablation process.

[0042] At operation 302, as shown in Figure 4B, a portion of the resist 430 is removed to expose a portion of the first seal 212. At operation 303, as shown in Figure 4C, the portion of the first seal 212 exposed by the resist 430 and a portion of the coating 210 are removed to expose an edge portion 220 of the substrate 201. The portion of the first seal 212 and the portion of the coating 210 are removed using etching or ashing.

[0043] At operation 304, as shown in Figure 4D, an edge black 214 is disposed over the first seal 212, the coating 210, and the substrate 201. The edge black 214 is disposed over an edge portion 215 the first seal 212, and edge 216 of the first seal 212, and an edge 217 of the coating 210, and an edge portion 220 of the substrate201. The edge black 214 is deposited using screen printing, needle dispensing, or inkjet printing.

[0044] At operation 305, as shown in Figure 4E, a protective coating (PC) 332 is globally disposed over the first seal 212 and the edge black 214. The PC 332 is deposited using screen printing, needle dispensing, or inkjet printing. The PC 332 includes polymer materials, such as water soluble materials, organic soluble materials, or otherwise strippable.

[0045] At operation 306, as shown in Figure 4F, the partial waveguide 400A is diced to form the edge blacked waveguide combiner 200A. The partial waveguide 400A is diced using a waterjet guided laser. The PC 332 provides protection for the partial waveguide 400A during the dicing process, as the dicing process typically produces debris that can cause damage to the edge blacked waveguide combiner 200A. At operation 307, as shown in Figure 4G, the PC 332 is removed. The PC 332 is removed by ashing or sonication.

[0046] Figure 5 is a flow chart of a method 500 of forming a double sealed edge blacked waveguide combiner 200B. Figures 6A-6H are cross-sectional view of the double sealed edge blacked waveguide combiner 200B during the method 500.

[0047] At operation 501, as shown in Figure 6A, a resist 630 is disposed over a first seal 212 of a partial waveguide 600A. The first seal 212 is disposed over a coating 210. The coating 210 is disposed over a substrate 201. The resist 630 is a positive resist or a negative resist. A positive resist includes portions of the resist, which, when exposed to electromagnetic radiation, are respectively soluble to a resist developer applied to the resist after the pattern is written into the resist using the electromagnetic radiation. A negative resist includes portions of the resist, which, when exposed to radiation, will be respectively insoluble to the resist developer applied to the resist after the pattern is written into the resist using the electromagnetic radiation. The chemical composition of the resist 630 determines whether the resist 630 is a positive resist or a negative resist. The patterning is one of a photolithography, digital lithography process, or laser ablation process.

[0048] At operation 502, as shown in Figure 6B, a portion of the resist 630 is removed to expose a portion of the first seal 212. At operation 503, as shown inFigure 6C, the portion of the first seal 212 exposed by the resist 630 and a portion of the coating 210 are removed. Removing the portion of the first seal 212 and the coating 210 expose an edge portion 220 of the substrate 201. The portion of the first seal 212 and the portion of the coating 210 are removed using etching or ashing.

[0049] At operation 504, as shown in Figure 6D, a second seal 213 is disposed over the first seal 212, the coating 210, and the substrate 201. The second seal 213 is disposed over an edge 216 of the first seal 212, an edge 217 of the coating 210, and the edge portion 220 of the substrate 201 exposed by the removed portion of the first seal 212 and the removed portion of the coating 210. In addition to the processes used to deposit the first seal 212, the second seal 213 is deposited using chemical vapor deposition (CVD) or atomic layer deposition (ALD) in order to provide a more conformal seal to the coating 210. The first seal 212, the second seal 213, and the coating 210 together form a layer stack 255. In some embodiments, the layer stack 255 is disposed over a device layer 250, which is disposed over the substrate 201.

[0050] At operation 505, as shown in Figure 6E, a protective coating (PC) 632 is globally disposed over the second seal 213. The PC 332 is deposited using screen printing, needle dispensing, or inkjet printing.

[0051] At operation 506, as shown in Figure 6F, the partial waveguide 600A is diced into the double sealed edge blacked waveguide combiner 200B. The partial waveguide 600A is diced using a water jet guided laser. The PC 632 provides protection for the partial waveguide 600A during the dicing process, as the dicing process typically produces debris that can cause damage to the double sealed edge blacked waveguide combiner 200B.

[0052] At operation 507, as shown in Figure 6G, the PC 632 is removed. The PC 632 is removed by ashing or sonication. At operation 508, as shown in Figure 6H, an edge black 214 is disposed over the second seal 213, the first seal 212, the coating 210, and the substrate 201. The edge black 214 is disposed on an edge portion 219 the second seal 213, an edge 221 of the second seal 213, and an edge 218 of the substrate 201. The edge black 214 is deposited using screen printing, needle dispensing, or inkjet printing.

[0053] Figure 7 is a flow chart of a method 700 of forming an extended edge blacked waveguide combiner 200C. Figures 8A-8G are cross-sectional view of the extended edge blacked waveguide combiner 2000 during the method 700.

[0054] At operation 701, as shown in Figure 8A, a resist 830 is disposed over a first seal 212 of a partial waveguide. The first seal 212 is disposed over a coating 210. The coating 210 is disposed over a substrate 201. The first seal 212 and the coating 210 together form a layer stack 255. In some embodiments, the layer stack 255 is disposed over a device layer 250, which is disposed over the substrate 201. The resist 830 is a positive resist or a negative resist. A positive resist includes portions of the resist, which, when exposed to electromagnetic radiation, are respectively soluble to a resist developer applied to the resist after the pattern is written into the resist using the electromagnetic radiation. A negative resist includes portions of the resist, which, when exposed to radiation, will be respectively insoluble to the resist developer applied to the resist after the pattern is written into the resist using the electromagnetic radiation. The chemical composition of the resist 830 determines whether the resist 830 is a positive resist or a negative resist. The patterning is one of a photolithography, digital lithography process, or laser ablation process.

[0055] At operation 702, as shown in Figure 8B, the resist 830 is partially removed to expose a portion of the first seal 212. At operation 703, as shown in Figure 8C, the portion of the first seal 212 exposed by the resist 830 and a portion of the coating 210 are removed. The removal of the portion of the first seal the portion of the coating expose an edge portion 220 of the substrate 201. The portion of the first seal 212 and the portion of the coating 210 are removed using etching cr ashing.

[0056] At operation 704, as shown in Figure 8D, an ashable coating 833 is globally disposed over the first seal 212, the coating an edge 216 of the first seal 212, and an edge 217 of the coating 210. The ashable coating 833 is deposited using screen printing, needle dispensing, or inkjet printing.

[0057] At operation 705, as shown in Figure 8E, the partial waveguide is diced into the extended edge blacked waveguide combiner 200C. The partial waveguide is diced using a waterjet guided laser. The ashable coating 833 provides protection for the partial waveguide during the dicing process, as the dicing process typicallyproduces debris that can cause damage to the extended edge blacked waveguide combiner 200C.

[0058] At operation 706, as shown in Figure 8F, the ashable coating 833 is removed. The ashable coating 833 is removed by ashing. The ashable coating includes polymer coatings, such as polymers made from carbon (C), nitrogen (N), oxygen (O), hydrogen (H), or a combination thereof.

[0059] At operation 707, as shown in Figure 8G, an edge black 214 is disposed over the first seal, the coating 210, and the substrate 201. The edge black 214 is disposed over an edge portion 215 the first seal 212, edge 216 of the first seal 212, and an edge 217 of the coating 210, and an edge portion 220 of the substrate 201. The edge black 214 is deposited using screen printing, needle dispensing, or inkjet printing.

[0060] In summary, methods of forming a waveguide combiner are disclosed. The waveguide includes a substrate, a coating, one or more seals, and an edge black. The coating is a porous silica, a fluorinated polymer, or other material having a refractive index (Rl) from about 1.03 to about 1.3. The coating prevents or reduces light leakage by trapping the light that is propagating through the waveguide within the waveguide. The seals includes a metal oxide or an organic material. The seals have a Rl from about 1.15 to about 2.0 and provide a protective seal for the coating to prevent moisture and debris from contaminating the porous coating. The edge black absorbs light at the edges of the waveguide combiner to improve image contrast and provides a barrier layer for the coating to prevent moisture and debris from contaminating the porous coating.

[0061] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

What is claimed is:1 . A device, comprising:a substrate;a coating disposed over a substrate and having a first refractive index from about 1.03 to about 1.3, wherein an edge portion of the substrate is exposed by the coating;a first seal disposed over the coating and having a second refractive index of about 1.15 to about 2.0;a second seal disposed over the first seal, and edge of the first seal, an edge of the coating, and the edge portion of the substrate and having a third refractive index of about 1.15 to about 2.0; andan edge black disposed over an edge portion of the second seal, an edge of the second seal, and an edge of the substrate.

2. The device of claim 1, wherein the coating is a porous silica or a fluorinated polymer.

3. The device of claim 1 , wherein the coating has a thickness of about 0.8 pm to about 1.2 pm.

4. The device of claim 1 , wherein the edge black is polydimethylsiloxane (PDMS), polyacrylate, epoxy, polyimide, or polystyrene.

5. The device of claim 1, wherein the first seal and the second seal has a thickness of about 2 nm to about 100 pm.

6. The device of claim 1 , wherein the third refractive index is different from the second refractive index.

7. The device of claim 1, wherein the first seal and the second seal is a silicon oxide (SiC>2), silicon oxynitride (SiON), aluminum oxide (AIO), silicon nitride (SiN), polydimethylsiloxane (PDMS), polyacrylate, epoxy, polyimide, or polystyrene.

8. An augmented reality waveguide, comprising:a substrate;at least one grating disposed over the substrate;an edge coating material disposed over an edge portion of the substrate; and a layer stack disposed over the substrate between the at least one grating and the edge portion of the substate, the layer stack comprising:a coating having a first refractive index from about 1.03 to about 1.3; anda first seal having a second refractive index of about 1.15 to about 2.0, wherein the edge coating material is disposed on the edge portion of the substrate, on sidewalls of the coating and the first seal adjacent to the edge portion, and over an upper surface of the layer stack.

9. The augmented reality waveguide of claim 8, wherein the coating is a porous silica or a fluorinated polymer.

10. The augmented reality waveguide of claim 8, wherein the coating has a thickness of about 0.8 pm to about 1.2 pm.

11. The augmented reality waveguide of claim 8, wherein the coating has a refractive index (Rl) from about 1 .03 to about 1.3.

12. The augmented reality waveguide of claim 8, wherein the first seal has a thickness of about 2 nm to about 100 pm.

13. The augmented reality waveguide of claim 8, wherein the first seal is a silicon oxide (SiC>2), silicon oxynitride (SiON), aluminum oxide (AIO), silicon nitride (SiN), polydimethylsiloxane (PDMS), polyacrylate, epoxy, polyimide, or polystyrene.

14. The augmented reality waveguide of claim 8, wherein the edge black is polydimethylsiloxane (PDMS), polyacrylate, epoxy, polyimide, or polystyrene.

15. A device, comprising:a substrate;a coating disposed over a substrate and having a first refractive index from about 1.03 to about 1.3, wherein an edge portion of the substrate is exposed by the coating;a first seal disposed over the coating and having a second refractive index of about 1.15 to about 2.0; andan edge black disposed over an edge portion of the first seal, an edge of the first seal, an edge of the coating, the edge portion of the substrate, and an edge of the substrate.

16. The device of claim 15, wherein the coating is a porous silica or a fluorinated polymer.

17. The device of claim 15, wherein the coating has a thickness of about 0.8 pm to about 1.2 pm.

18. The device of claim 15, wherein the edge black is polydimethylsiloxane (PDMS), polyacrylate, epoxy, polyimide, or polystyrene.

19. The device of claim 15, wherein the first seal is a silicon oxide (SiO2), silicon oxynitride (SiON), aluminum oxide (AIO), silicon nitride (SiN), polydimethylsiloxane (PDMS), polyacrylate, epoxy, polyimide, or polystyrene.

20. The device of claim 15, wherein the first seal has a thickness of about 2 nm to about 100 pm.

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