Wafer-level direct bonding using dispensable optically clear adhesive for augmented reality glasses lamination

Abstract

Embodiments of the present disclosure generally relate to augmented reality (AR) displays. More specifically, embodiments described herein relate to an AR lens assembly and methods of forming such assemblies. In some embodiments, a method of forming a lens assembly includes disposing an optically clear adhesive onto a surface of a wafer level optical stack. The method further includes exposing the optically clear adhesive to an ultraviolet (UV) source to at least partially cure the optically clear adhesive. The method further includes laminating a substrate onto the optically clear adhesive to form a wafer level optical assembly. The method further includes post-processing the optical assembly to form a plurality of lens assemblies.

Description

WAFER-LEVEL DIRECT BONDING USING DISPENSABLE OPTICALLY CLEAR ADHESIVE FOR AUGMENTED REALITY GLASSES LAMINATIONBACKGROUNDField

[0001] Embodiments of the present disclosure generally relate to augmented reality (AR) displays. More specifically, embodiments described herein relate to an AR lens assembly and methods of forming such assemblies.Description of the Related Art

[0002] 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 headmounted 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 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. Conventional AR device fabrication methods can include laminating a waveguide with other optical layers, such as cover lenses, push-pull lenses, and / or prescription lenses. Such optical layers may be laminated to the waveguide using a direct bonding design, which utilizes a low index coating as the external media on the waveguide wherein the incident beams of light of a virtual image diffract and undergo total-internal- reflection (TIR) through the waveguide.

[0004] One downside of this approach is that the direct bonding design requires the use of an adhesive layer to adhere the optical layers, such as cover lenses, push-pull lenses, and / or prescription lenses, to the low index coating. Conventional methods of applying such adhesive materials include liner removal steps when using an adhesive film and / or require the use of dam structures during fabrication to contain a liquid resin adhesive. In addition, such conventionaladhesive application processes are conducted on the scale of die level fabrication. Such aspects of conventional adhesive application processes can deleteriously affect device fabrication throughput, cost effectiveness, and yield.

[0005] Thus, there is a need to develop more effective device fabrication and / or adhesive application processes.SUMMARY

[0006] Embodiments of the present disclosure generally relate to augmented reality (AR) displays. More specifically, embodiments described herein relate to an AR lens assembly and methods of forming such assemblies.

[0007] In some embodiments, a method of forming a lens assembly includes disposing an optically clear adhesive onto a surface of a wafer level optical stack. The method further includes exposing the optically clear adhesive to an ultraviolet (UV) source to at least partially cure the optically clear adhesive. The method further includes laminating a substrate onto the optically clear adhesive to form a wafer level optical assembly. The method further includes post-processing the optical assembly to form a plurality of lens assemblies.

[0008] In some embodiments, a method of forming a lens assembly includes disposing a first optically clear adhesive onto a first surface of a wafer level optical stack. The method further includes exposing the first optically clear adhesive to an ultraviolet (UV) light to at least partially cure the first optically clear adhesive. The method further includes laminating a first wafer level substrate onto a surface of the first optically clear adhesive. The method further includes bonding the first wafer level substrate onto the first surface of the wafer level optical stack by progressing a first cure profile of the first optically clear adhesive. The method further includes disposing a second optically clear adhesive onto a second surface of the wafer level optical stack. The method further includes exposing the second optically clear adhesive to the UV light to at least partially cure the second optically clear adhesive. The method further includes laminating a second wafer level substrate onto a surface of the second optically clear adhesive. The method further includes bonding the second wafer level substrate onto the second surface of the wafer level optical stack to form an optical assembly. The second wafer level substrate is bound to the second surface ofthe wafer level optical stack by progressing a second cure profile of the second optically clear adhesive. The method further includes dicing the optical assembly to form the lens assembly.

[0009] In some embodiments, an assembly includes a waveguide comprising a world-side surface and an eye-side surface. The waveguide is a component of a wafer level optical stack. The assembly further includes a first adhesive layer disposed on a world-side surface of the optical stack and a second adhesive layer disposed on an eye-side surface of the optical stack. The assembly further includes a first substrate disposed on the first adhesive layer and a second substrate disposed on the second adhesive layer, wherein at least one of the first substrate and the second substrate is a wafer level 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 of the disclosure and are therefore not to be considered limiting of its scope, as the disclosure may admit to other equally effective embodiments.

[0011] Figure 1 is a schematic, frontal view of a waveguide, according to an embodiment.

[0012] Figure 2 is a cross-sectional view of an ophthalmic lens assembly, according to an embodiment.

[0013] Figure 3 is a process flow diagram of a method, according to an embodiment.

[0014] Figure 4 is a process flow diagram of a method, according to an embodiment.

[0015] 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

[0016] Methods disclosed herein relate to the fabrication of a lens assembly, such as an ophthalmic lens assembly. More specifically, the methods disclosed herein allow for wafer level fabrication of a lens assembly and direct bonding a substrate and / or lens to the surfaces of an optical stack. Furthermore, the lens fabrication methods disclosed herein are conducted on the scale of wafer level fabrication. Being able to fabricate lens assemblies at the wafer level allows for a more simplified process flow over traditional lens fabrication methods by eliminating traditional liner removal steps and / or the requirement for using dam structures during fabrication. The wafer level fabrication processes disclosed herein are more efficient over traditional die level fabrication processes in terms of throughput, cost effectiveness, and yield.

[0017] Figure 1 is a schematic, frontal view of a waveguide 100. It is to be understood that the waveguide 100 described herein is an exemplary waveguide and that other waveguides may be used with or modified to accomplish aspects of the present disclosure. The waveguide 100 includes a plurality of structures 102. The structures 102 may be disposed over, under, or on a first surface 103 of a substrate 101 , or disposed in the substrate 101. The structures 102 are nanostructures and have a sub-micron critical dimension, e.g., a width less than 1 micrometer. Regions of the structures 102 correspond to one or more gratings 104. In one embodiment, which can be combined with other embodiments described herein, the waveguide 100 includes at least a first grating 104a corresponding to an input coupling grating and a third grating 104c corresponding to an output coupling grating. In another embodiment, which can be combined with other embodiments described herein, the waveguide 100 further includes a second grating 104b. The second grating 104b corresponds to a pupil expansion grating or a fold grating.

[0018] The substrate 101 can be any substrate used in the art, and can be either opaque or transparent to a chosen wavelength of light, depending on the use of the substrate 101 as a substrate for a waveguide. Substrate selection may include substrates of any suitable material, including, but not limited to, amorphous dielectrics, non-amorphous dielectrics, crystalline dielectrics,polymers, or combinations thereof. In some embodiments, the substrate 101 includes, but is not limited to, a silicon-containing material, a silicon and oxygen containing compound, a germanium-containing material, an indium and phosphide containing compound, a gallium and arsenic containing compound, a gallium and nitrogen containing compound, a carbon-containing material, a silicon and carbon containing compound, a silicon, carbon, and oxygen containing compound, a silicon and nitrogen containing compound, a silicon, oxygen, and nitrogen containing compound, a niobium and oxygen containing compound, a lithium, niobium, and oxygen containing compound, an aluminum and oxygen containing compound, an indium, tin, and oxygen containing compound, a titanium and oxygen containing compound, a lanthanum and oxygen containing compound, a gadolinium and oxygen containing compound, a zinc and oxygen containing compound, an yttrium and oxygen containing compound, a tungsten and oxygen containing compound, a potassium, and oxygen containing compound, a phosphorous and oxygen containing compound, a barium and oxygen containing compound, a sodium and oxygen containing compound, or combinations thereof.

[0019] In other embodiments, which can be combined with other embodiments described herein, the substrate 101 includes an oxide including one or more of gadolinium, silicon, sodium, barium, potassium, tungsten, phosphorus, zinc, calcium, titanium, tantalum, niobium, lanthanum, zirconium, lithium, or yttrium containing-materials. Example materials of the substrate 101 include silicon (Si), silicon monoxide (SiO), silicon dioxide (SiC>2), silicon carbide (SiC), fused silica, diamond, quartz germanium (Ge), silicon germanium (SiGe), indium phosphide (InP), gallium arsenide (GaAs), gallium nitride (GaN), sapphire, sapphire (AI2O3), lithium niobate (LiNbOs), indium tin oxide (ITO), lanthanum oxide (La20s), gadolinium oxide (Gd20s), zinc oxide (ZnO), yttrium oxide (Y2O3), tungsten oxide (WO3), titatium oxide (TiO2), zirconium oxide (ZrOs), sodium oxide (Na2O), niobium oxide (Nb20s), barium oxide (BaO), potassium oxide (K2O), phosphorus pentoxide (P2O5), calcium oxide (CaO), or combinations thereof. The substrate 101 may have a refractive index greater than about 1.8. For example, the substrate 101 includes lithium niobate.

[0020] The structures 102 include a structure material. The structure material and the substrate 101 include a different material. The structure material includes, but is not limited to, one or more oxides, carbides, or nitrides of silicon, aluminum, zirconium, tin, tantalum, zirconium, barium, titanium, hafnium, lithium, lanthanum, cadmium, niobium, or combinations thereof. Example materials of the structure material include silicon carbide, silicon oxycarbide, titanium oxide, silicon oxide, vanadium oxide, aluminum oxide, aluminum-doped zinc oxide, indium tin oxide, tin oxide, zinc oxide, tantalum oxide, silicon nitride, zirconium oxide, niobium oxide, cadmium stannate, silicon oxynitride, barium titanate, diamond like carbon, hafnium oxide, lithium niobate, silicon carbon-nitride, silver, cadmium selenide, mercury telluride, zinc selenide, silver-indium-gallium-sulfur, silver-indium-sulfur, indium phosphide, gallium phosphide, lead sulfide, lead selenide, zinc sulfide, molybdenum sulfide, tungsten sulfide, or combinations thereof.

[0021] In operation of the waveguide 100, a virtual image is projected from a near-eye display, such as a microdisplay, to the first grating 104a. The structures 102 of the first grating 104a in-couple the incident beams of light of the virtual image and diffract the incident beams to the second grating 104b. The diffracted beams undergo total-internal-reflection (TIR) through the waveguide 100 until the diffracted beams come in contact with structures 102 of the second grating 104b. The diffracted beams from the first grating 104a incident on the second grating 104b are split into a first portion of beams refracted back or lost in the waveguide 100, a second portion beams that undergo TIR in the second grating 104b until the second portion beams contact another structure of the plurality of structures 102 of the second grating 104b, and a third portion of beams that are transmitted through the waveguide 100 to the third grating 104c. The beams of the second portion of beams that undergo TIR in the second grating 104b continue to contact structures of the plurality of structures 102 until either the intensity of the second portion of beams coupled through the waveguide 100 to the second grating 104b is depleted, or a remaining portion of the second portion of beams propagating through the second grating 104b reach the end of the second grating 104b.

[0022] The beams pass through the waveguide 100 to the third grating 104c and undergo TIR in the waveguide 100 until the beams contact a structure of the plurality of gratings 104 of the third grating 104c. The beams are split into beams that are refracted back or lost in the waveguide 100. Beams undergo TIR in the third grating 104c until the beams contact another structure of the plurality of gratings 104 or the beams are out-coupled from the waveguide 100. The beams that undergo TIR in the third grating 104c continue to contact structures of the plurality of gratings 104 until either the intensity of the beams pass through the waveguide 100 to the third grating 104c is depleted, or a remaining portion of the beams propagating through the third grating 104c have reached the end of the third grating 104c. The beams of the virtual image are propagated from the third grating 104c to overlay the virtual image over the ambient environment.

[0023] Figure 2 is a cross-sectional view of an ophthalmic lens assembly 200. The ophthalmic lens assembly 200 may include one or more components, such as a waveguide 100, an anti-reflective coating (ARC) 202, a low index coating 204, a cap layer 206, an adhesive 208, a world-side lens 210a, and an eye-side lens 210b. In some embodiments, each of the ARC 202, the low index coating 204, the cap layer 206, and the adhesive 208 may independently be disposed on the world-side surface of the waveguide 100, the eye-side surface of the waveguide 100, or both. In at least one embodiment, the lens array includes a waveguide 100, a world-side ARC 202a, an eye-side ARC 202b, a world-side low index coating 204a, an eye-side low index coating 204b, a world-side cap layer 206a, an eye-side cap layer 206b, a world-side adhesive 208a, an eye-side adhesive 208b, a world-side lens 210a, and an eye-side lens 210b.

[0024] The ARC 202 can include any suitable coating known to one of ordinary skill in the art. The ARC 202 may be disposed over the world-side surface of the waveguide (e.g., world-side ARC 202a), the eye-side surface of the waveguide (e.g., eye-side ARC 202b), or both. The ARC 202 may be deposited by any suitable method known to one of ordinary skill in the art, such as chemical vapor deposition (CVD), flowable CVD (FCVD), physical vapor deposition (PVD), atomic layer deposition (ALD), spin coating, ink jetting, screen printing, spray coating, and the like. In one or more embodiments, the ARC 202 is deposited atan appropriate thickness that decreases the reflectivity made by the method of deposition. In at least one embodiment, the ARC 202 includes alternating layers of SiO2 and TiO2 or alternating layers of SiO2 and ZrO2. In at least one embodiment, the ARC 202 includes a SiO2 layer deposited by FCVD at a thickness of about 95 nm.

[0025] The low index coating 204 can include any suitable coating known to one of ordinary skill in the art. The low index coating 204 may be disposed over the surface of the world-side ARC 202a (e.g., world-side low index coating 204a), the surface of the eye-side ARC 202b (e.g., eye-side low index coating 204b), or both. In some embodiments, the low index coating includes an optically clear coating having a refractive index (Rl) of about 1 .3 or less. The low index coating 204 may be made up of porous silica and / or one or more fluorinated polymers. In at least one embodiment, the low index coating 204 is a porous silica coating with a Rl of 1 .15.

[0026] The cap layer 206 can include a suitable barrier layer capable of preventing an adhesive material from contacting and / or leaking into the low index coating 204. The cap layer 206 may be disposed over the surface of the worldside low index coating 204a (e.g., world-side cap layer 206a), the surface of the eye-side low index coating 204b (e.g., eye-side cap layer 206b), or both. In some embodiments, the cap layer 206 can be made up of SiO, AIO, and / or any one or more suitable organic coatings. The cap layer 206 may be deposited via any one or more suitable methods known to one of ordinary skill in the art, such as CVD, FCVD, PVD, ALD, spin coating, ink jetting, screen printing, spray coating, and the like.

[0027] In some embodiments, the ophthalmic lens assembly 200 includes an optical stack 207, such as a wafer level optical stack. The optical stack 207 may include one or more of the waveguide 100, the ARC 202, the low index coating 204, and the cap layer 206. In at least one embodiment, the optical stack 207 includes the waveguide 100. In at least one embodiment, the optical stack 207 includes the waveguide 100 and the ARC 202 disposed over a surface of the waveguide 100. In at least one embodiment, the optical stack 207 includes the waveguide 100, the ARC 202 disposed over a surface of the waveguide 100, andthe low index coating 204 disposed over a surface of the ARC 202. In at least one embodiment, the optical stack 207 includes the waveguide 100, the ARC 202 disposed over a surface of the waveguide 100, the low index coating 204 disposed over a surface of the ARC 202, and the cap layer 206 disposed over a surface of the low index coating 204.

[0028] The adhesive 208 can include any suitable adhesive material capable of adhering a lens, such as the world-side lens 210a and / or the eye-side lens 210b, to the optical stack 207. The adhesive 208 may include an optically clear adhesive (OCA). In at least one embodiment, the adhesive 208 is an OCA configured as an adhesive film. The adhesive film may include two liners that may be sequentially removed therefrom. For instance, the first liner may be removed to expose a first surface of the adhesive film to be brought into contact with a surface of a lens. The second liner may then be removed to expose a second surface of the adhesive to be brought into contact with a surface of the optical stack 207. In at least one embodiment, the adhesive 208 is a resin based adhesive. The resin based adhesive may be dispensed onto either a surface of a lens and / or a surface of the optical stack 207 to adhere the lens and optical stack together by means of curing the resin based adhesive. The resin based adhesive may be cured by any suitable means known to one of ordinary skill in the art, as determined by the reactive mechanism of the resin based adhesive. In one or more embodiments, the resin based adhesive may be cured via a thermal cure process, exposure to ultraviolet (UV) light, or a combination thereof. The adhesive 208 may include one or more acrylic and / or silicon based resins and / or films.

[0029] In some embodiments, the ophthalmic lens assembly 200 may be configured to include one of either the world-side lens 210a or the eye-side lens 210b and the corresponding adhesive (e.g., the world-side adhesive 208a or the eye-side adhesive 208b) connecting the selected lens to the optical stack 207. That is to say that the ophthalmic lens assembly 200 may be manufactured, via one or more methods discussed below, to include only one lens disposed on either the world-side or eye-side of the optical stack. In such an embodiment, the side of the resulting ophthalmic lens assembly 200 opposite the lens may be openfor further processing, treatment, and / or lens assembly modification methods known to one of ordinary skill in the art.

[0030] Figure 3 is a process flow diagram depicting a method 300 of preparing an ophthalmic lens assembly 200. The method 300 includes a process by which an adhesive 208 may be disposed onto an optical stack 207 and adhered to a substrate and / or lens (e.g., the world-side lens 210a and / or the eye-side lens 210b). In operation 310 of the method 300, the adhesive 208 (e.g., a resin based adhesive) is disposed onto a surface of the optical stack 207. The adhesive 208 may be disposed onto a surface of the optical stack 207 by any suitable process known to one of ordinary skill in the art, such as spin coating, ink jetting, screen printing, blade coating, and the like. In at least one embodiment, the disposal process of operation 310 is a wafer level process. The adhesive 208 may be a resin based adhesive having a viscosity suitable for the disposal process of operation 310. The adhesive 208 may be a resin based adhesive suitable for a UV curing process and / or a thermal curing process. In at least one embodiment, the adhesive 208 includes an acrylate system and / or an epoxy system, such that the adhesive includes one or more monomers, crosslinkers, oligomers, and combinations thereof. The adhesive 208 may also include a photoinitiator and / or a photosensitizer. In at least one embodiment, the adhesive 208 includes a thixotorpy index (Tl) modifier, such as fumed silica and / or carbon black, to increase Tl for needle dispensing and screen printing. In at least one embodiment, the adhesive 208 includes a surface energy modifier, such as a silicon based or fluorinated or Pluronic surfactant. The adhesive 208 may also include an adhesion promoter. In at least one embodiment, the viscosity of the adhesive 208 ranges from about 1 cP to about 5x107cP, such as about 50 cP to about 5x106cP, such as about 500 cP to about 5x105cP.

[0031] In operation 320 of the method 300, the adhesive 208 disposed over a surface of the optical stack 207 is at least partially cured via exposure to a UV source. In at least one embodiment, the UV exposure process of operation 320 is a wafer level process. Exposing the adhesive 208 to a UV source initiates a cure reaction that increases the viscosity of the adhesive 208 as the reaction progresses. In some embodiments, the adhesive 208 disposed over a surface ofthe optical stack 207 is exposed to a UV source having an intensity of about 1 m J / cm2to about 1000 J / cm2, such as about 10 J / cm2to about 100 J / cm2for about 1 second to about 1 hr, such as about 1 min to about 10 min.

[0032] In operation 330 of the method 300, a substrate is laminated over the at least partially cured adhesive 208 disposed over a surface of the optical stack 207. In at least one embodiment, the lamination process of operation 330 is a wafer level process. The substrate to be laminated on the at least partially cured adhesive 208 may include a wafer level substrate, a die level substrate, or a combination thereof. In some embodiments, the substrate includes a lens, such as the world-side lens 210a and / or the eye-side lens 210b. The substrate may be laminated over the at least partially cured adhesive 208 by any process known to one of ordinary skill in the art.

[0033] In operation 340 of the method 300, the optical stack 207 with a substrate laminated over a surface thereof (herein interchangeably referred to as an “optical assembly”) is subjected to a post-processing process. In at least one embodiment, the optical assembly is a wafer level optical assembly. The postprocessing process may include a series of bonding and / or dicing operations. In at least one embodiment, the post-processing process of operation 340 includes a bonding process to bond the substrate to the surface of the optical stack 207 by progressing the cure profile of the adhesive 208. The bonding process may include thermally annealing the adhesive 208 of the optical assembly to bond the substrate to the surface of the optical stack 207. In one or more embodiments, the bonding process includes: 1 ) applying a vacuum to the optical assembly, 2) applying a pressure to compress the optical stack 207, and 3) thermally annealing the adhesive 208 (e.g., within an autoclave chamber) to fortify the lamination. In at least one embodiment, the post-processing process of operation 340 includes dicing the optical assembly to a die level structure. In some embodiments, operation 340 of the method 300 includes the bonding process and the dicing process, which may be performed simultaneously or sequentially. In at least one embodiment, operation 340 of the method 300 includes first subjecting the optical assembly to the bonding process and then to the dicing process. In at least one embodiment, operation 340 of the method 300 includes first subjecting the opticalassembly to the dicing process and then to the bonding process. In at least one embodiment, operation 340 of the method 300 results in the formation of a plurality of diced optical assemblies.

[0034] In at least one embodiment, the method 300 is conducted such that the ophthalmic lens assembly 200 is configured to include one of either the worldside lens 210a or the eye-side lens 210b and the corresponding adhesive (e.g., the world-side adhesive 208a or the eye-side adhesive 208b) connecting the selected lens to the optical stack 207. That is to say, that the resulting ophthalmic lens assembly 200 is manufactured to include only one lens disposed on either the world-side or eye-side of the optical stack. In such an embodiment, the side of the resulting ophthalmic lens assembly 200 opposite the lens may be open for further processing, treatment, and / or lens assembly modification methods known to one of ordinary skill in the art.

[0035] Figure 4 is a process flow diagram depicting a method 400 of preparing an ophthalmic lens assembly 200. The method 400 includes a process by which an adhesive 208 may be disposed onto a first surface of an optical stack 207 and a second surface of an optical stack 207, and adhering a substrate and / or lens (e.g., the world-side lens 210a and / or the eye-side lens 210b) to both the first and second surfaces of the optical stack 207. In operation 410 of the method 400, the adhesive 208 (e.g., a resin based adhesive) is disposed onto a first surface of the optical stack 207. The adhesive 208 may be disposed onto the first surface of the optical stack 207 by any suitable process known to one of ordinary skill in the art, such as spin coating, ink jetting, screen printing, blade coating, and the like. In at least one embodiment, the disposal process of operation 410 is a wafer level process. The adhesive 208 may be a resin based adhesive having a viscosity suitable for the disposal process of operation 410. The adhesive 208 may be a resin based adhesive suitable for a UV curing process and / or a thermal curing process. In at least one embodiment, the adhesive 208 includes an acrylate system and / or an epoxy system, such that the adhesive 208 includes one or more monomers, crosslinkers, oligomers, and combinations thereof. The adhesive 208 may also include a photoinitiator and / or a photosensitizer. In at least one embodiment, the adhesive 208 includes a thixotorpy index (Tl) modifier, such asfumed silica and / or carbon black, to increase Tl for needle dispensing and screen printing. In at least one embodiment, the adhesive 208 includes a surface energy modifier, such as a silicon based or fluorinated or Pluronic surfactant. The adhesive 208 may also include an adhesion promoter. In at least one embodiment, the viscosity of the adhesive 208 ranges from about 1 cP to about 5x107cP, such as about 50 cP to about 5x106cP, such as about 500 cP to about 5x105cP.

[0036] In operation 420 of the method 400, the adhesive 208 disposed over the first surface of the optical stack 207 is at least partially cured via exposure to a UV source. In at least one embodiment, the UV exposure process of operation 420 is a wafer level process. Exposing the adhesive 208 to a UV source initiates a cure reaction that increases the viscosity of the adhesive 208 as the reaction progresses. In some embodiments, the adhesive 208 disposed over a first surface of the optical stack 207 is exposed to a UV source having an intensity of about 1 mJ / cm2to about 1000 J / cm2, such as about 10 J / cm2to about 100 J / cm2for about 1 second to about 1 hr, such as about 1 min to about 10 min.

[0037] In operation 430 of the method 400, a substrate is laminated over the at least partially cured adhesive 208 disposed over a first surface of the optical stack 207. In at least one embodiment, the lamination process of operation 430 is a wafer level process. The substrate to be laminated on the at least partially cured adhesive 208 may include a wafer level substrate, a die level substrate, or a combination thereof. In some embodiments, the substrate includes a lens, such as the world-side lens 210a and / or the eye-side lens 210b. The substrate may be laminated over the at least partially cured adhesive 208 by any process known to one of ordinary skill in the art.

[0038] In operation 440 of the method 400, the optical stack 207 with a substrate laminated over a first surface thereof is subjected to a bonding process. In at least one embodiment, the bonding process of operation 440 is a wafer level process. In at least one embodiment, the bonding process includes bonding the substrate to the first surface of the optical stack 207 by progressing the cure profile of the adhesive 208. The bonding process may include thermally annealing the adhesive 208 of the optical assembly to bond the substrate to thefirst surface of the optical stack 207. In at least one embodiment, the bonding process includes any one or more bonding processes previously described herein.

[0039] In operation 450 of the method 400, the adhesive 208 (e.g., a resin based adhesive) is disposed onto a second surface of the optical stack 207. The adhesive 208 may be disposed onto the second surface of the optical stack 207 by any suitable process known to one of ordinary skill in the art, such as spin coating, ink jetting, screen printing, blade coating, and the like. In at least one embodiment, the disposal process of operation 450 is a wafer level process. The adhesive 208 may be a resin based adhesive having a viscosity suitable for the disposal process of operation 450, such as any suitable adhesive previously described herein. The adhesive 208 may be a resin based adhesive suitable for a UV curing process and / or a thermal curing process.

[0040] In operation 460 of the method 400, the adhesive 208 disposed over the second surface of the optical stack 207 is at least partially cured via exposure to a UV source. In at least one embodiment, the UV exposure process of operation 460 is a wafer level process. Exposing the adhesive 208 to a UV source initiates a cure reaction that increases the viscosity of the adhesive 208 as the reaction progresses. In some embodiments, the adhesive 208 disposed over a second surface of the optical stack 207 is exposed to a UV source having an intensity of about 1 mJ / cm2to about 1000 J / cm2, such as about 10 J / cm2to about 100 J / cm2for about 1 second to about 1 hr, such as about 1 min to about 10 min.

[0041] In operation 470 of the method 400, a substrate is laminated over the at least partially cured adhesive 208 disposed over a second surface of the optical stack 207. In at least one embodiment, the lamination process of operation 470 is a wafer level process. The substrate to be laminated on the at least partially cured adhesive 208 may include a wafer level substrate, a die level substrate, or a combination thereof. In some embodiments, the substrate includes a lens, such as the world-side lens 210a and / or the eye-side lens 210b. The substrate may be laminated over the at least partially cured adhesive 208 by any process known to one of ordinary skill in the art.

[0042] In operation 480 of the method 400, the optical stack 207 with a substrate laminated over a second surface thereof is subjected to a bonding process to form an optical assembly. In at least one embodiment, the bonding process of operation 480 is a wafer level process. In at least one embodiment, the bonding process includes bonding the substrate to the second surface of the optical stack 207 by progressing the cure profile of the adhesive 208. The bonding process may include thermally annealing the adhesive 208 of the optical assembly to bond the substrate to the second surface of the optical stack 207. In at least one embodiment, the bonding process includes any one or more bonding processes previously described herein.

[0043] In operation 490 of the method 400, the optical assembly prepared in operation 480 is subjected to a dicing operation to configure the optical assembly into an ophthalmic lens assembly 200. The dicing operation may include any one or more suitable dicing operations known to one of ordinary skill in the art, such as one or more laser dicing operations.

[0044] Overall, the methods disclosed herein relate to the fabrication of a lens assembly, such as an ophthalmic lens assembly. More specifically, the methods disclosed herein allow for wafer level fabrication of a lens assembly and direct bonding of a substrate and / or lens (e.g., the world-side lens 210a and / or the eyeside lens 210b) to the surfaces of an optical stack. Being able to fabricate lens assemblies at the wafer level allows for a more simplified process flow over traditional lens fabrication methods by eliminating traditional liner removal steps and / or the requirement for using dam structures during fabrication. In other words, the wafer level fabrication processes disclosed herein, such as the wafer level lamination process disclosed herein, are more efficient over traditional die level fabrication processes in terms of throughput, cost effectiveness, and yield.

[0045] 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

We claim:1 . A method of forming a lens assembly, the method comprising: disposing an optically clear adhesive onto a surface of a wafer level optical stack; exposing the optically clear adhesive to an ultraviolet (UV) source to at least partially cure the optically clear adhesive; laminating a substrate onto the optically clear adhesive to form a wafer level optical assembly; and post-processing the wafer level optical assembly to form a plurality lens of assemblies.

2. The method of claim 1 , wherein the wafer level optical stack comprises: a waveguide; a first coating disposed over a surface of the waveguide, the first coating comprising an anti-reflective coating; a second coating disposed over a surface of the first coating, the second coating comprising a refractive index of about 1 .3 or less; and a cap layer disposed over a surface of the second coating.

3. The method of claim 2, wherein the optically clear adhesive is disposed over a surface of the cap layer.

4. The method of claim 1 , wherein the optically clear adhesive is disposed onto the surface of the wafer level optical stack by spin coating, ink jetting, screen printing, or blade coating.

5. The method of claim 1 , wherein the UV source comprises an intensity of about 1 mJ / cm2to about 1000 J / cm2.

6. The method of claim 1 , wherein the optically clear adhesive is exposed to the UV source for about 1 second to about 1 hour.

7. The method of claim 1 , wherein post-processing the wafer level optical assembly comprises: bonding the substrate to the wafer level optical stack to form an optical stack; and dicing the optical stack to form the plurality of lens assemblies.

8. The method of claim 1 , wherein post-processing the wafer level optical assembly comprises: dicing the wafer level optical assembly to form a plurality of diced optical assemblies, wherein at least one of the plurality of diced optical assemblies comprises a diced substrate and a diced optical stack; and bonding the diced substrate to the diced optical stack to form the lens assembly.

9. A method of forming a lens assembly, the method comprising: disposing a first optically clear adhesive onto a first surface of a wafer level optical stack; exposing the first optically clear adhesive to an ultraviolet (UV) light to at least partially cure the first optically clear adhesive; laminating a first wafer level substrate onto a surface of the first optically clear adhesive; bonding the first wafer level substrate onto the first surface of the wafer level optical stack by progressing a first cure profile of the first optically clear adhesive; disposing a second optically clear adhesive onto a second surface of the wafer level optical stack; exposing the second optically clear adhesive to the UV light to at least partially cure the second optically clear adhesive; laminating a second wafer level substrate onto a surface of the second optically clear adhesive; bonding the second wafer level substrate onto the second surface of the wafer level optical stack to form an optical assembly, the second wafer levelsubstrate being bound to the second surface of the wafer level optical stack by progressing a second cure profile of the second optically clear adhesive; and dicing the optical assembly to form the lens assembly.

10. The method of claim 9, wherein the wafer level optical stack comprises: a waveguide comprising a world-side surface and an eye-side surface; a first coating disposed over the world-side surface of the waveguide, the first coating comprising a first anti-reflective coating; a second coating disposed over the eye-side surface of the waveguide, the second coating comprising a second anti-reflective coating; a third coating disposed over a surface of the first coating, the third coating comprising a refractive index of about 1 .3 or less; a fourth coating disposed over a surface of the second coating, the fourth coating a refractive index of about 1 .3 or less; a first cap layer disposed over a surface of the third coating; and a second cap layer disposed over a surface of the fourth coating.

11. The method of claim 10, wherein the first optically clear adhesive is disposed over a surface of the first cap layer, and the second optically clear adhesive is disposed over a surface of the second cap layer.

12. The method of claim 9, wherein the first optically clear adhesive is disposed onto the first surface of the wafer level optical stack by spin coating, ink jetting, screen printing, or blade coating.

13. The method of claim 9, wherein the second optically clear adhesive is disposed onto the second surface of the wafer level optical stack by spin coating, ink jetting, screen printing, or blade coating.

14. The method of claim 9, wherein the UV light comprises an intensity of about 1 mJ / cm2to about 1000 J / cm2.

15. The method of claim 9, wherein both the first optically clear adhesive and the second optically clear adhesive are independently exposed to the UV light for about 1 second to about 1 hour.

16. An assembly, comprising: a waveguide comprising a world-side surface and an eye-side surface, wherein the waveguide is a component of a wafer level optical stack; a first adhesive layer disposed on a world-side surface of the wafer level optical stack and a second adhesive layer disposed on an eye-side surface of the wafer level optical stack; and a first substrate disposed on the first adhesive layer and a second substrate disposed on the second adhesive layer, wherein at least one of the first substrate and the second substrate is a wafer level substrate.

17. The assembly of claim 16, wherein the wafer level optical stack comprises: a first coating disposed over the world-side surface of the waveguide, the first coating comprising a first anti-reflective coating; a second coating disposed over the eye-side surface of the waveguide, the second coating comprising a second anti-reflective coating; a third coating disposed over a surface of the first coating, the third coating comprising a refractive index of about 1 .3 or less; a fourth coating disposed over a surface of the second coating, the fourth coating comprising a refractive index of about 1 .3 or less; a first cap layer disposed over a surface of the third coating; and a second cap layer disposed over a surface of the fourth coating.

18. The assembly of claim 17, wherein the first adhesive layer is disposed over a surface of the first cap layer, and the second adhesive layer is disposed over a surface of the second cap layer.

19. The assembly of claim 16, wherein the first adhesive layer is either UV curable or thermally curable independent of the second adhesive layer.

20. The assembly of claim 16, wherein at least one of the first substrate and the second substrate is a die level substrate.

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