Inkjet inks for deposition and removal in laser dicing processes

Abstract

A method of dicing optical devices from an optical device substrate is provided. The method includes disposing a protective coating over only the optical devices. The optical device substrate includes a plurality of optical devices disposed on a surface thereof with areas between them. The areas of the optical device substrate are exposed by the protective coating. The protective coating includes a polymer, a solvent, and an additive. The method further includes curing the protective coating through a curing process such that the protective coating is water soluble after the solvent is removed by the curing process, dicing the optical devices from the optical device substrate by projecting a laser beam onto the areas between the optical devices, and exposing the protective coating to water to remove the protective coating from the diced optical devices.

Description

[Background technology]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 268,504, filed February 25, 2022, the entire contents of which are incorporated by reference herein. [Technical field]

[0002]

[0002] Embodiments of the present disclosure relate generally to optical devices. In particular, embodiments of the present disclosure relate to methods of laser dicing optical devices having protective coatings and protective coatings for laser dicing optical devices.

[0003] 2. Description of Related Art

[0001] Virtual reality (VR) is generally considered to be a computer-generated simulated environment in which a user has an apparent physical presence. Virtual reality (VR) experiences are generated in 3D and can be viewed on a head-mounted display (HMD) (e.g., glasses or other wearable display device with near-eye display panels as lenses to display a virtual reality environment that replaces the real environment).

[0004]

[0002] Augmented reality (AR), however, allows an experience in which a user can see the surrounding environment by looking through the display lenses of glasses or other HMD devices, but can also see images of virtual objects that are generated for display and appear as part of this environment. AR may include any type of input (e.g., audio input and haptic input), as well as virtual images, graphics, and videos that enhance or extend the environment experienced by the user. To achieve an AR experience, virtual images are superimposed on the surrounding environment, which is performed by optical devices.

[0005]

[0003] Multiple optical devices are fabricated on a substrate and then diced before being used in VR and AR devices. Therefore, there is a need for a method of laser dicing optical devices with a protective coating, and a protective coating for laser dicing optical devices. Summary of the Invention

[0006]

[0004] A method of dicing optical devices from an optical device substrate is provided. The method includes disposing a protective coating over only the optical devices. The optical device substrate includes a plurality of optical devices disposed on a surface thereof with areas between them. The areas of the optical device substrate are exposed by the protective coating. The protective coating includes a polymer, a solvent, and an additive. The method further includes curing the protective coating through a curing process such that the protective coating is water soluble after the solvent is removed by the curing process, dicing the optical devices from the optical device substrate by projecting a laser beam onto the areas between the optical devices, and exposing the protective coating to water to remove the protective coating from the diced optical devices.

[0007]

[0005] A method of dicing optical devices from an optical device substrate is provided. The method includes depositing a protective coating by inkjet deposition or screen printing deposition onto only the optical devices. The optical device has a plurality of optical device structures disposed thereon. The optical device substrate includes a plurality of optical devices disposed on a surface thereof with areas between them. The areas of the optical device substrate are exposed by the protective coating. The protective coating includes a polymer, a solvent, and an additive. The method further includes curing the protective coating through a curing process such that the protective coating is water soluble after the solvent is removed by the curing process, dicing the optical devices from the optical device substrate by projecting a laser beam onto the areas between the optical devices, and exposing the protective coating to water to remove the protective coating from the diced optical devices.

[0008]

[0006] A method of dicing optical devices from an optical device substrate is provided. The method includes depositing a protective coating by inkjet deposition or screen printing deposition only onto the optical devices. The optical device has a plurality of optical device structures disposed thereon. The optical device substrate includes a plurality of optical devices disposed on a surface thereof with areas between them. The areas of the optical device substrate are exposed by the protective coating. The protective coating includes a polymer. The polymer includes at least one of a polyvinylpyrrolidone (PVP)-containing material, a polypropylene-containing material, a polyvinyl acetate (PVA)-containing material, or combinations thereof, a solvent, and an additive. The method further includes curing the protective coating through a curing process such that the protective coating is water soluble after the solvent is removed by the curing process, dicing the optical devices from the optical device substrate by projecting a laser beam onto the areas between the optical devices, and exposing the protective coating to water to remove the protective coating from the diced optical devices.

[0009]

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

[0010] [Figure 1A] FIG. 2 is a perspective front view of an optical device substrate according to embodiments described herein. [Figure 1B] FIG. 2 is a perspective front view of an optical device substrate according to embodiments described herein. [Diagram 2] FIG. 1 is a flow diagram of a method for dicing optical devices. [Figure 3A-3D] 1A-1C are schematic cross-sectional views of a portion of an optical device substrate during a method for dicing optical devices according to embodiments described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011]

[0012] For ease of understanding, the same reference numbers have been used, where possible, to designate identical elements common to the figures. It is envisioned that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

[0012]

[0013] FIELD OF THE DISCLOSURE Embodiments of the present disclosure relate generally to optical devices, and more particularly to methods of laser dicing optical devices having protective coatings and protective coatings for laser dicing optical devices.

[0013]

[0014] FIG. 1A is a schematic perspective view of an optical device substrate 101. The optical device substrate 101 includes a plurality of optical devices 100 disposed on a surface 103 of the optical device substrate 101. The optical device 100 is a waveguide combiner utilized for virtual reality, augmented reality, or mixed reality. The optical device substrate 101 may be any substrate used in the art and may be either opaque or transparent to a selected laser wavelength depending on the application of the optical device substrate 101. Furthermore, the optical device substrate 101 may have a variety of shapes, thicknesses, and diameters. For example, the optical device substrate 101 may have a diameter of about 150 mm to about 300 mm. The optical device substrate 101 may have a circular, rectangular, or square shape. The optical device substrate 101 may have a thickness between about 300 μm and about 1 mm. Although only nine optical devices 100 are shown on the optical device substrate 101, any number of optical devices 100 may be disposed on the surface 103.

[0014]

[0015] FIG. 1B is a perspective front view of the optical device substrate 100. It should be understood that the optical device 100 described herein is an exemplary optical device, and other optical devices can be combined or modified to achieve aspects of the present disclosure. The optical device 100 includes a plurality of optical device structures 102 disposed on a surface 103 of an optical device substrate 101. The optical device structures 102 may be nanostructures having submicron dimensions (e.g., nano-sized dimensions). Areas of the optical device structures 102 correspond to one or more gratings, such as a first grating 104a and a second grating 104b. In some embodiments that can be combined with other embodiments described herein, the optical device 100 includes at least a first grating 104a corresponding to an input coupling grating and a second grating 104b corresponding to an output coupling grating. The optical device structures 102 may have other shapes, including, but not limited to, circular, triangular, elliptical, regular polygonal, irregular polygonal, and / or irregularly shaped cross sections.

[0015]

[0016] After fabricating the optical devices 100 on the optical device substrate 101, it is desirable to dice the optical device substrate 101 into individual optical devices. For example, as shown in FIG. 3D, further described herein, a first optical device 100A and a second optical device 100B are diced from the substrate into individual optical devices. To improve the quality of the optical devices 100 after dicing, contamination that occurs during the dicing process must be reduced. The method 200 described herein provides for dicing of the optical devices 100 with reduced contamination through the use of a water-soluble protective coating that is selectively deposited on the optical devices 100 prior to dicing.

[0016]

[0017] Figure 2 is a flow diagram of a method 200 for dicing optical devices 100 from an optical device substrate 101. Figures 3A-3D are schematic cross-sectional views of a portion 301 of the optical device substrate 101 during the performance of the method 200. The portion 301 of the optical device substrate 101 corresponds to a first optical device 100A and a second optical device 100B to be diced from the optical device substrate 101.

[0017]

[0018] In operation 201, a protective coating 302 is deposited only on the optical device 100. A portion of the surface 103 of the optical device substrate 101 without the optical device 100 is not coated with the protective coating 302. As shown in FIG. 3A, the protective coating 302 is deposited only on the first optical device 100A and the second optical device 100B. The protective coating 302 is deposited by inkjet deposition or screen printing deposition. The inkjet deposition or screen printing deposition results in selective deposition of the protective coating 302 only on the optical device 100. The protective coating 302 may reflect, refract, or diffract the laser beam during the laser dicing process. The reflection, refraction, or diffraction of the laser beam may lead to undesired laser dose or other consequences, which may cause the area 304 of the optical device substrate 101 without the optical device 100 to not be completely removed. Depositing the protective coating 302 only on the optical device 100 allows for complete removal of the areas 304 of the optical device substrate 101 exposed by the protective coating 302 after the laser dicing process. Before curing, the protective coating 302 for inkjet printing has a viscosity of 0.5 centipoise (cP) to 200 cP at 25° C. Before curing, the protective coating 302 for screen printing has a viscosity of 1000 centipoise (cP) to 100,000 cP at 25° C. Before curing, the protective coating 302 has a surface tension of 15 milliNewtons per meter (mN / m) to 90 mN / m.

[0018]

[0019] The protective coating 302 includes a polymer, a solvent, and an additive. In some embodiments, the protective coating 302 further includes a photocurable material. The polymer includes at least one of a polyvinylpyrrolidone (PVP)-containing material, a polypropylene-containing material, a polyvinyl acetate (PVA)-containing material, or a combination thereof. The PVP-containing material includes at least one of a PVP polymer, a PVD copolymer, a PVD block copolymer, or a combination thereof. The polymer is hydrophilic and water-soluble. The hydrophilic and water-soluble polymer allows the protective coating 302 to be soluble in water after the protective coating 302 is cured by UV irradiation, thermal baking, or a combination thereof. The thermal baking is performed at a temperature of 25° C. or more and 300° C. or less. The water may be deionized water or distilled water.

[0019]

[0020] The photocurable material includes one or more monomers, crosslinkers, oligomers, photoinitiators, or combinations thereof. The photocurable material crosslinks into a water-soluble polymer network when the protective coating 302 is cured. The water-soluble polymer network makes the protective coating 302 water-soluble. In some embodiments, the protective coating 302 is cured by a UV curing process or a thermal baking process. The monomer includes a water-soluble acrylic acid, such as methacrylic acid, an epoxy, or a combination thereof. The crosslinker includes a water-soluble multifunctional acrylate, such as a multifunctional acrylate, a methacrylate, an epoxy, or a combination thereof. The oligomer includes a water-soluble acrylate, a methacrylate, an epoxy, or a combination thereof. The additive includes one or more surfactants or one or more polymers.

[0020]

[0021] The solvent includes organic solvents and water. The organic solvents include esters, ethers, and alcohols. The esters, ethers, and alcohols have a boiling point of 300° C. or less at 1 atm. The organic solvents include di(propylene glycol) methyl ether (DPGDME), dipropylene glycol n-butyl ether (DPGBE), tri(propylene glycol) methyl ether (TPGME), dipropylene glycol mono-n-propyl ether (DPGPE), dipropylene glycol dimethyl ether (DPGDME), tripropylene glycol (mono) n-butyl ether (TPGBE), propylene glycol butyl ether (PGBE), (2-(2-methoxyethoxy)ethanol (DEGME), 2-(2-ethoxyethoxy)ethanol (DEGEE), triethylene glycol monomethyl ether (TEGME), propylene glycol methyl ether (PGME ), propylene glycol propyl ether (PGPE), propylene glycol methyl ether acetate (PGMEA), dipropylene glycol monomethyl ether acetate (DPGMEA), ethanol, methanol, isopropanol, 1-butanol, 2-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 1-hexanol, 2-hexanol, 3-hexanol, butyl acetate, butyl lactate, or combinations thereof. The solvent includes 0% to 80% water. The solvent allows the protective coating 302 to be selectively deposited as an inkjet ink or a screen printing ink. Upon curing, the solvent is removed from the protective coating 302.

[0021]

[0022] In operation 202, as shown in FIG. 3B, the protective coating 302 is cured. The protective coating 302 is cured by a baking process or a UV curing process. Once cured, the solvent is removed from the protective coating 302. In some embodiments, the protective coating 302 is cured by a baking process. In other embodiments, the protective coating 302 is cured by a UV curing process. In operation 203, the optical device 100 is diced. The area 304 of the optical device substrate 101 substrate exposed by the protective coating 302 is removed by a dicing process. The dicing process is a laser dicing process. During the laser dicing process, a laser beam is projected onto the area 304. Because the protective coating 302 is deposited only on the optical device 100, the area 304 of the optical device substrate 101 exposed by the protective coating 302 is completely removed after the laser dicing process. As shown in FIG. 3C, first optical device 100A and second optical device 100B are diced from portion 301 of optical device substrate 101 and region 304 is removed.

[0022]

[0023] In operation 204, the protective coating 302 is removed from the optical device 100. As shown in FIG. 3D, the protective coating 302 is removed from the first optical device 100A and the second optical device 100B. The protective coating 302 is removed by exposure to water. The water may be deionized water or distilled water. Because the protective coating 302 is water-soluble, removing the protective coating 302 with water produces aqueous waste. Organic waste from insoluble coatings, such as organic coatings, may contaminate the optical device 100.

[0023]

[0024] While the forgoing 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, the scope of the disclosure being determined by the following claims.

Claims

1. 1. A method for dicing optical devices from an optical device substrate, comprising: disposing a protective coating over only the optical devices, the optical device substrate including a plurality of the optical devices disposed on a surface thereof with areas therebetween, the areas of the optical device substrate being exposed by the protective coating, the protective coating comprising: polymer, Solvent, and Additives disposing a protective coating comprising: hardening the protective coating through a curing process such that the protective coating is water soluble after the solvent is removed by the curing process; dicing the optical devices from the optical device substrate by projecting a laser beam into the areas between the optical devices; removing the protective coating from the diced optical devices by exposing the protective coating to water; A method comprising:

2. The method of claim 1 , wherein the solvent comprises an organic solvent and water.

3. The method of claim 2 , wherein the organic solvent comprises an ester, an ether, and an alcohol.

4. 4. The method of claim 3, wherein the ester, the ether, and the alcohol have boiling points of 300° C. or less at 1 atm.

5. The organic solvent is di(propylene glycol) methyl ether (DPGDME), dipropylene glycol n-butyl ether (DPGBE), tri(propylene glycol) methyl ether (TPGME), dipropylene glycol mono-n-propyl ether (DPGPE), dipropylene glycol dimethyl ether (DPGDME), tripropylene glycol (mono) n-butyl ether (TPGBE), propylene glycol butyl ether (PGBE), (2-(2-methoxyethoxy)ethanol (DEGME), 2-(2-ethoxyethoxy)ethanol (DEGEE), tri ... tripropylene glycol dimethyl ether (DPGDME), tripropylene glycol mono-n-butyl ether (TPGBE), propylene glycol butyl ether (PGBE), (2-(2-methoxyethoxy)ethanol (DEGME), 2-(2-ethoxyethoxy)ethanol (DEGEE), tripropylene glycol mono-n-propyl ether (DPGPE), tripropylene glycol mono-n-propyl ether (DPGPE), tripropylene glycol mono-n-propyl ether (DPGPE), tripropylene glycol mono-n-butyl ether (TPGBE), tripropylene glycol mono-n-butyl ether (TPGBE), tripropylene glycol mono-n-butyl ether (TPGBE), tripropylene glycol mono-n-butyl ether (PGBE), tripropylene glycol mono-n-butyl ether (PGBE), tripropylene glycol mono-n-butyl ether (PGBE), tripropylene glycol mono-n-butyl ether (PGBE), tripropylene glycol mono-n-butyl ether (PGBE), tripropylene glycol mono-n-butyl ether (PGBE), tripropylene glycol mono-n-butyl ether (PGBE), tripropylene glycol mono-n-butyl ether (PG 4. The method of claim 3, comprising ethylene glycol monomethyl ether (TEGME), propylene glycol methyl ether (PGME), propylene glycol propyl ether (PGPE), propylene glycol methyl ether acetate (PGMEA), dipropylene glycol monomethyl ether acetate (DPGMEA), ethanol, methanol, isopropanol, 1-butanol, 2-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 1-hexanol, 2-hexanol, 3-hexanol, butyl acetate, butyl lactate, or combinations thereof.

6. The method of claim 1 , wherein the polymer comprises at least one of a polyvinylpyrrolidone (PVP)-containing material, a polypropylene-containing material, a polyvinyl acetate (PVA)-containing material, or a combination thereof.

7. The method of claim 6 , wherein the PVP-containing material comprises at least one of a PVP polymer, a PVD copolymer, a PVD block copolymer, or a combination thereof.

8. The method of claim 1 , wherein the protective coating further comprises a photocurable material.

9. The method of claim 8 , wherein the photocurable material comprises one or more monomers, crosslinkers, oligomers, photoinitiators, or combinations thereof.

10. The method of claim 1 , wherein the optical device has a plurality of optical device structures disposed thereon.

11. The method of claim 10 , wherein the areas of the plurality of optical device structures correspond to one or more gratings.

12. The method of claim 1 , wherein the polymer is hydrophilic and water soluble.

13. The method of claim 1 , wherein the protective coating is deposited over only the optical device by inkjet deposition or screen printing deposition.

14. 1. A method for dicing optical devices from an optical device substrate, comprising: disposing a protective coating over only the optical device by inkjet deposition or screen printing deposition, the optical device having a plurality of optical device structures disposed thereon, the optical device substrate including a plurality of the optical devices disposed on a surface thereof with areas therebetween, the areas of the optical device substrate being exposed by the protective coating, the protective coating comprising: A polymer that is hydrophilic and water soluble; Solvent, and Additives disposing a protective coating comprising: hardening the protective coating through a curing process such that the protective coating is water soluble after the solvent is removed by the curing process; dicing the optical devices from the optical device substrate by projecting a laser beam into the areas between the optical devices; removing the protective coating from the diced optical devices by exposing the protective coating to water; A method comprising:

15. The method of claim 14 , wherein the solvent comprises an organic solvent and water.

16. 16. The method of claim 15, wherein the organic solvent comprises an ester, an ether, and an alcohol.

17. 17. The method of claim 16, wherein the ester, the ether, and the alcohol have a boiling point of 300° C. or less at 1 atm.

18. The organic solvent is di(propylene glycol) methyl ether (DPGDME), dipropylene glycol n-butyl ether (DPGBE), tri(propylene glycol) methyl ether (TPGME), dipropylene glycol mono-n-propyl ether (DPGPE), dipropylene glycol dimethyl ether (DPGDME), tripropylene glycol (mono) n-butyl ether (TPGBE), propylene glycol butyl ether (PGBE), (2-(2-methoxyethoxy)ethanol (DEGME), 2-(2- ...

16. The method of claim 15, comprising the step of: diethylene glycol monomethyl ether (DEGEE), triethylene glycol monomethyl ether (TEGME), propylene glycol methyl ether (PGME), propylene glycol propyl ether (PGPE), propylene glycol methyl ether acetate (PGMEA), dipropylene glycol monomethyl ether acetate (DPGMEA), ethanol, methanol, isopropanol, 1-butanol, 2-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 1-hexanol.

19. The method of claim 14 , wherein the areas of the plurality of optical device structures correspond to one or more gratings.

20. 1. A method for dicing optical devices from an optical device substrate, comprising: disposing a protective coating over only the optical device by inkjet deposition or screen printing deposition, the optical device having a plurality of optical device structures disposed thereon, the optical device substrate including a plurality of the optical devices disposed on a surface thereof with areas therebetween, the areas of the optical device substrate being exposed by the protective coating, the protective coating comprising: a polymer comprising at least one of a polyvinylpyrrolidone (PVP)-containing material, a polypropylene-containing material, a polyvinyl acetate (PVA)-containing material, or a combination thereof; Solvent, and Additives disposing a protective coating comprising: hardening the protective coating through a curing process such that the protective coating is water soluble after the solvent is removed by the curing process; dicing the optical devices from the optical device substrate by projecting a laser beam into the areas between the optical devices; removing the protective coating from the diced optical devices by exposing the protective coating to water; A method comprising:

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