Low-frequency imprinting for grayscale optical device fabrication

Abstract

Some embodiments described herein relate to a method for forming a waveguide having a grating of a structure with a depth distribution, the method including: disposing a resist material over an area of ​​a device material or a substrate corresponding to the grating of the structure to be formed with the depth distribution; imprinting a stamp into the resist material over the area, the stamp having a positive pattern of the depth distribution, wherein imprinting the stamp and hardening the resist material forms patterned resist over the area; imprinting the stamp; releasing the stamp; etching the patterned resist and one of the device material or the substrate to form the depth distribution in the device material or the substrate; and forming a structure in the area with the depth distribution to form the grating.

Description

[Technical Field]

[0001]

[0001] Embodiments of the present disclosure generally relate to waveguides. In particular, embodiments described herein provide a method for forming a waveguide having a grating with a depth profile. [Background technology]

[0002]

[0002] Virtual reality is generally considered to be a computer-generated simulated environment in which a user has an apparent physical presence. The virtual reality experience is generated in 3D and can be viewed with a head-mounted display (HMD), such as glasses or other wearable display devices. The HMD has a near-eye display panel as the eyepiece of an optical device for displaying a virtual reality environment that replaces the real environment.

[0003]

[0003] However, augmented reality enables an experience in which a user can still see the surrounding environment through the eyepieces of the optical device of a pair of glasses or other HMD device, but can also see images of virtual objects that are displayed and appear to be part of the environment. Augmented reality can also include any type of input, such as audio input or tactile input, as well as virtual images, graphics, and video that enhance or augment the environment the user is experiencing. As an emerging technology, augmented reality has many challenges and design constraints.

[0004] What is needed in the art is a method for forming a waveguide having a grating with a depth profile. Summary of the Invention

[0005] In one embodiment, a method is provided that includes disposing a resist material over an area of ​​a device material or a substrate corresponding to a grating of a structure to be formed having a depth distribution, imprinting a stamp into the resist material over the area, the stamp having a positive pattern of the depth distribution, wherein imprinting the stamp and hardening the resist material forms patterned resist over the area, imprinting the stamp, releasing the stamp, etching the patterned resist and one of the device material or the substrate to form the depth distribution in the device material or substrate, and forming a structure in the area having the depth distribution to form the grating.

[0006] In another embodiment, a method is provided that includes depositing a resist material on a positive pattern on a stamp, the positive pattern corresponding to a depth distribution of a grating of a structure to be formed, inverting the stamp so that the resist material is disposed on areas of a device material or substrate that correspond to the grating of the structure to be formed having the depth distribution, curing to form patterned resist over the areas, releasing the stamp, etching the patterned resist and one of the device material or substrate to form the depth distribution in the device material or substrate, and forming a structure in the area with the depth distribution to form the grating.

[0007] In yet another embodiment, a method is provided that includes disposing a resist material on a patterned hard mask, the patterned hard mask being disposed over a device material or a substrate, the resist material being disposed over areas of the device material or substrate corresponding to a grating of a structure having a depth distribution to be formed, disposing the resist material, imprinting a stamp into the resist material over the areas, the stamp having a positive pattern of the depth distribution, the imprinting of the stamp and hardening of the resist material forming patterned resist over the areas, imprinting the stamp, releasing the stamp, and etching the patterned resist and one of the device material or the substrate to form a grating of a structure having a depth distribution in the device material or the substrate.

[0008]

[0008] So that the features of the present disclosure described above may be understood in detail, a more particular description of the present disclosure briefly summarized above may be had by reference to several embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the attached drawings depict only exemplary embodiments and therefore should not be considered to limit the scope of the present disclosure, as other equally effective embodiments may also be permissible. [Brief explanation of the drawings]

[0009] [Figure 1]

[0009] FIG. 1 is a perspective front view of a waveguide according to an embodiment. [Figure 2A]

[0010] 2 is a cross-sectional view of a portion of a waveguide in a first configuration according to an embodiment. FIG. [Figure 2B]

[0011] FIG. 10 is a cross-sectional view of a portion of a waveguide in a second configuration according to an embodiment. [Figure 3A]

[0012] 2A-2C are schematic cross-sectional views of a substrate during a first method according to an embodiment. [Figure 3B] 2A-2C are schematic cross-sectional views of a substrate during a first method according to an embodiment. [Figure 3C] 2A-2C are schematic cross-sectional views of a substrate during a first method according to an embodiment. [Figure 4A]

[0013] 5A-5C are schematic cross-sectional views of a stamp during a second method according to an embodiment. [Figure 4B]

[0014] 5A-5C are schematic cross-sectional views of a substrate during a second method according to an embodiment. [Figure 4C] 5A-5C are schematic cross-sectional views of a substrate during a second method according to an embodiment. [Figure 4D] 5A-5C are schematic cross-sectional views of a substrate during a second method according to an embodiment. [Figure 5A]

[0015] 5A-5C are schematic cross-sectional views of a substrate during a third method according to an embodiment. [Figure 5B] 5A-5C are schematic cross-sectional views of a substrate during a third method according to an embodiment. [Figure 5C] 5A-5C are schematic cross-sectional views of a substrate during a third method according to an embodiment. [Figure 5D] 5A-5C are schematic cross-sectional views of a substrate during a third method according to an embodiment. [Figure 6A]

[0016] 1 is a schematic cross-sectional view of a stamp according to an embodiment. [Figure 6B] 1 is a schematic cross-sectional view of a stamp according to an embodiment. [Figure 6C] 1 is a schematic cross-sectional view of a stamp according to an embodiment. [Figure 6D] 1 is a schematic cross-sectional view of a stamp according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010]

[0017] For ease of understanding, wherever possible, like reference numerals have been used to designate like 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.

[0011]

[0018] Embodiments described herein relate to methods for forming a waveguide having a grating with a depth profile structure.

[0012]

[0019] FIG. 1 illustrates a perspective front view of a waveguide 100. The waveguide 100 described herein is an exemplary waveguide, and it should be understood that other waveguides may be used or modified to implement aspects of the present disclosure. The waveguide 100 includes a plurality of structures 102. The structures 102 may be disposed above, below, or on a surface 103 of a substrate 101 (FIG. 2B), or may be disposed within the substrate 101 (FIG. 2A). The structures 102 are nanostructures having a submicron 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 may 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 dilation grating or a folding grating. The structure 102 of the grating 104 needs to be adjusted to control the intensity of the beam so as to adjust the field of view of the virtual image generated from the microdisplay from the user's viewpoint and increase the viewing angle at which the user can see the virtual image. To adjust the grating 104, the structure 102 has a depth distribution.

[0013]

[0020] Figure 2A is a cross-sectional view of a portion of a waveguide 100 in a first configuration 200a according to several embodiments. Figure 2B is a cross-sectional view of a portion of a waveguide 100 in a second configuration 200b according to several embodiments.

[0014]

[0021] The waveguide 100 of the first configuration 200a includes a grating 104 having a structure 102 disposed within a substrate 101. The waveguide 100 of the second configuration 200b includes a grating 104 having a structure 102 disposed on or above the substrate 101. The structure 102 of the second configuration 200b includes a device material 211. The substrate 101 includes a substrate of any suitable material, including, but not limited to, an amorphous dielectric, a non-amorphous dielectric, a crystalline dielectric, a silicon-containing material, a polymer, and combinations thereof. In one embodiment, which may be combined with other embodiments described herein, the substrate 101 is made of one or more of silicon (Si), silicon dioxide (SiO), silicon carbide (SiC), fused silica, diamond, or quartz material. In another embodiment, which may be combined with other embodiments described herein, the substrate 101 is comprised of one or more of nitrogen-, titanium-, niobium-, lanthanum-, zirconium-, or yttrium-containing materials. The device material 211 may be, but is not limited to, silicon carbide (SiC), silicon oxycarbide (SiOC), titanium dioxide (TiO), silicon dioxide (SiO), vanadium(IV) oxide (VO), or a combination thereof. x ), aluminum oxide (Al2O3), aluminum-doped zinc oxide (AZO), indium tin oxide (ITO), tin dioxide (SnO2), zinc oxide (ZnO), tantalum pentoxide (Ta2O5), silicon nitride (Si3N4), zirconium dioxide (ZrO2), niobium oxide (Nb2O5), cadmium stannate (Cd2SnO4), silicon mononitride (SiN), silicon oxynitride (SiON), barium titanate (BaTiO3), diamond-like carbon (DLC), hafnium(IV) oxide (HfO2), lithium niobate (LiNbO3), silicon carbonitride (SiCN), or a combination thereof.

[0015]

[0022] The grating 104 has a depth profile 201 from the first end 202 to the second end 204. The depth profile 201 corresponds to the change in depth 206 of the channels 208 between adjacent structures 102. FIGS. 6A-6D are cross-sectional views of stamps according to embodiments. In one embodiment, which may be combined with other embodiments described herein, the depth profile 201 is linear as the depth 206 of the channels 208 changes from the first end 202 to the second end 204. Methods 300-500 utilize a first stamp 601 to form two gratings 104, such as a first grating 104a and a third grating 104c, having a depth profile 201 that is linear. As shown in FIG. 6A, a stamp structure 605 of the first stamp 601 includes an imprinted portion 606 that is a positive of (i.e., corresponds to) the linear depth profile 201. Methods 300-500 utilize a second stamp 602 to form one grating 104, such as first grating 104a, having a linear depth distribution 201 and another grating 104, such as third grating 104c, having a uniform depth distribution 201. As shown in FIG. 6B, stamp structure 605 of second stamp 602 includes one imprinted portion 606 that is a positive of linear depth distribution 201 and another imprinted portion 606 that corresponds to uniform depth distribution 201. As shown in FIG. 2B, third grating 104c has a uniform depth distribution 201. That is, the depth 206 of depth distribution 201 of channel 208 is the same from first end 202 to second end 204. Methods 300-500 utilize a fourth stamp 604 that includes an imprinted portion 606 that is uniform for two gratings 104 that have uniform depth distributions 201. Methods 300-500 utilize a third stamp 603 that includes an imprinted portion 606 that is a positive of the non-linear depth distribution 201. The grating 104 thereby has a depth distribution 201 that is non-linear from the first end 202 to the second end 204.

[0016]

[0023] As shown in FIGS. 6A-6D, the stamp structure 605 is bonded to a stamp substrate 607. The stamp structure 605 may include, but is not limited to, polydimethylsiloxane (PDMS), UV-curable acrylate, epoxy, polyurethane, or a combination thereof. The stamp substrate 607 may include, but is not limited to, polyethylene terephthalate (PET), glass, silica, or a combination thereof. The stamp structure 605 and stamp substrate 607 are translucent, allowing the resist material to be cured by exposure to ultraviolet (UV) light. The stamp substrate 607 may have a thickness of about 10 μm to about 5 mm. The portion width 608 of the imprint portion 606 is about 100 μm to about 100 cm, resulting in a grating 104 having a grating width 210 of about 100 μm to about 100 cm. The distance from the stamp structure 605 to the stamp substrate 607 is less than 1 mm. The grating 104 may include any combination of linear, non-linear, or uniform depth distributions 201 to control the intensity of the beam so as to modulate the field of view of the virtual image generated from the microdisplay from the user's viewpoint and expand the viewing angle over which the user can view the virtual image.

[0017]

[0024] 3A-3C are schematic cross-sectional views of a substrate 101 during a first method 300 for forming a waveguide 100 having a depth profile 201 of a grating 104. In a first step of the first method 300, a patterned resist 306 having a negative pattern 308 is formed. The negative pattern 308 is the inverse of a stamp structure 605. In some embodiments, the negative pattern 308 is formed on the surface 103 of the substrate 101. In other embodiments, the negative pattern 308 is formed on the surface 103 of the substrate 101. The negative pattern 308 is the negative of the depth profile 201. The depth profile 201 can be any linear, non-linear, or uniform profile corresponding to the stamp structure 605. As shown in FIG. 3A, in one embodiment of the first step, a stamp, such as a first stamp 601, is imprinted on the surface 103 of the substrate 101 or on a resist material 304 disposed on the surface 103. In other embodiments, a second stamp 602, a third stamp 603, or a fourth stamp 605 is used. A resist material 304 is deposited via inkjet printing or spin coating. The resist material 304 is cured to form a patterned resist 306 with a negative pattern 308. After the patterned resist 306 is cured, the stamp is released, as shown in FIG. 3B. In a second step, the patterned resist 306 and the device material 211 or the substrate 101 are etched to form the waveguide 100. The waveguide 100 has a depth profile 201 in an area 210 corresponding to the grating 104, as shown in FIG. 3C. The grating 104 is formed by depositing a hard mask on the substrate 101 and placing photoresist on the substrate 101. The photoresist is patterned according to the desired grating pattern to expose the hard mask. The hard mask is then etched to expose the device material 211 or the substrate 101. The device material 211 or the substrate 101 is then etched to form the grating 104. The photoresist and hard mask are then removed.

[0018]

[0025] FIG. 4A is a schematic cross-sectional view of a stamp. The stamp may be a first stamp 601. In other embodiments, a second stamp 602, a third stamp 603, or a fourth stamp 605 is used. FIGS. 4B-4D are schematic cross-sectional views of a substrate 101 during a second method 400 for forming a waveguide 100 having a depth profile 201. In a first step of the second method 400, a resist material 304 is placed on a positive pattern of an imprint portion 606 of the stamp. In a second step, the stamp is inverted and placed on or above the surface 103 of the substrate 101. In a third step, the resist material 304 is hardened to form a patterned resist 306 having a negative pattern that is the inverse of the stamp structure 605. In one embodiment of the third step, the resist material 304 is hardened before the stamp is inverted. In another embodiment of the third step, the stamp is inverted and placed on or above the surface 103 of the substrate 101, and then the resist material 304 is hardened. In a fourth step, the substrate 101 or device material 211 with the patterned resist 306 is etched to form a depth profile 201 in the area 210 corresponding to the grating 104. The grating 104 is formed by depositing a hard mask on the substrate 101 and placing photoresist on the substrate 101. The photoresist is patterned according to the desired grating pattern to expose the hard mask. The hard mask is then etched to expose the device material 211 or substrate 101. The device material 211 or substrate 101 is then etched to form the grating 104. The photoresist and hard mask are then removed.

[0019]

[0026] 5A-5D are schematic cross-sectional views of a substrate 101 during a third method for forming a waveguide 100 having a grating with a depth profile 201. In a first step of the third method, a resist material 304 is disposed on a patterned hard mask 502. The patterned hard mask 502 is disposed on or above the surface 103 of the substrate 101. The patterned hard mask 502 is exposed to etching of the device material 211 or the substrate 101 to form each structure 102 of the grating 104. In a second step of the third method 500, a patterned resist 306 having a negative pattern 308 is formed. The negative pattern 308 is the inverse of the stamp structure 605. In some embodiments, the negative pattern 308 is formed on the surface 103 of the substrate 101. In other embodiments, the negative pattern 308 is formed on the surface 103 of the substrate 101. The negative pattern 308 is the negative of the depth distribution 201. The depth distribution 201 can be any linear, non-linear, or uniform distribution corresponding to the stamp structure 605. The resist material 104 is hardened to form a patterned resist 306 having the negative pattern 308. After the patterned resist 306 is formed, the stamp 400 is released, as shown in FIG. 5C. In a second step, the device material 211 or substrate 101 with the patterned resist 306 is etched to form a grating 104 having a structure 102 with a depth distribution 210. The patterned hard mask 502 is removed.

[0020]

[0027] Several embodiments described herein relate to methods for forming a waveguide having a grating structure with a depth profile. Each method utilizes a stamp having a stamp structure with an imprinted portion that is a positive of (i.e., corresponds to) the depth profile. The positive pattern of the imprinted portion is designed to correspond to the depth profile. An imprinted resist with a negative pattern controls the etch rate so that the device material or substrate contains the depth profile.

[0021]

[0028] While the above description 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 which is determined by the following claims.

Claims

1. disposing a resist material on an area of ​​the device material or substrate corresponding to a grating of a structure to be formed having a depth profile; imprinting a stamp into the resist material over the area, the stamp having a positive pattern of the depth profile, wherein imprinting the stamp and hardening the resist material forms patterned resist over the area; Releasing said stamp; Etching the patterned resist and one of the device material or the substrate to form the depth profile in the device material or the substrate; and forming the structure in the area having the depth profile to form the grating.

2. the grating includes a first grating and a second grating; the first depth profile of the first grating is linear, non-linear, or uniform; The method of claim 1 , wherein the second depth distribution of the second grating is linear, non-linear, or uniform.

3. The method of claim 2 , wherein the first depth profile and the second depth profile are different from each other.

4. 10. The method of claim 1, wherein the imprint portion of the stamp has a portion width of about 100 μm to about 100 cm, such that the grating has a grating width of about 100 μm to about 100 cm.

5. The substrate may be silicon (Si), silicon dioxide (SiO 2 ), silicon carbide (SiC), fused silica, diamond, quartz nitrogen, titanium, niobium, lanthanum, zirconium, yttrium, or a combination thereof.

6. The device materials include silicon carbide (SiC), silicon oxycarbide (SiOC), titanium dioxide (TiO 2 ), silicon dioxide (SiO 2 ), vanadium(IV) oxide (VO x ), aluminum oxide (Al 2 O 3 ), aluminum-doped zinc oxide (AZO), indium tin oxide (ITO), tin dioxide (SnO 2 ), zinc oxide (ZnO), tantalum pentoxide (Ta 2 O 5 ), silicon nitride (Si 3 N 4 ), zirconium dioxide (ZrO 2 ), niobium oxide (Nb 2 O 5 ), cadmium stannate (Cd 2 SnO 4 ), silicon mononitride (SiN), silicon oxynitride (SiON), barium titanate (BaTiO 3 ), diamond-like carbon (DLC), hafnium(IV) oxide (HfO 2 ), lithium niobate (LiNbO 3 ), silicon carbonitride (SiCN), or a combination thereof.

7. disposing a resist material on the positive pattern of the stamp, the positive pattern corresponding to the depth distribution of the grating of the structure to be formed; inverting and positioning the stamp so that the resist material is disposed on areas of device material or substrate corresponding to the grating of the structure being formed having the depth profile; curing to form a patterned resist over said areas; Releasing said stamp; Etching the patterned resist and one of the device material or the substrate to form the depth profile in the device material or the substrate; and forming the structure in the area having the depth profile to form the grating.

8. the grating includes a first grating and a second grating; the first depth profile of the first grating is linear, non-linear, or uniform; The method of claim 7 , wherein the second depth distribution of the second grating is linear, non-linear, or uniform.

9. The method of claim 8 , wherein the first depth profile and the second depth profile are different from each other.

10. 8. The method of claim 7, wherein the imprint portion of the stamp has a portion width of about 100 μm to about 100 cm, such that the grating has a grating width of about 100 μm to about 100 cm.

11. The substrate may be silicon (Si), silicon dioxide (SiO 2 8. The method of claim 7, wherein the metal comprises silicon carbide (SiC), fused silica, diamond, quartz nitride, titanium, niobium, lanthanum, zirconium, yttrium, or a combination thereof.

12. The device materials include silicon carbide (SiC), silicon oxycarbide (SiOC), titanium dioxide (TiO 2 ), silicon dioxide (SiO 2 ), vanadium(IV) oxide (VO x ), aluminum oxide (Al 2 O 3 ), aluminum-doped zinc oxide (AZO), indium tin oxide (ITO), tin dioxide (SnO 2 ), zinc oxide (ZnO), tantalum pentoxide (Ta 2 O 5 ), silicon nitride (Si 3 N 4 ), zirconium dioxide (ZrO 2 ), niobium oxide (Nb 2 O 5 ), cadmium stannate (Cd 2 SnO 4 ), silicon mononitride (SiN), silicon oxynitride (SiON), barium titanate (BaTiO 3 ), diamond-like carbon (DLC), hafnium(IV) oxide (HfO 2 ), lithium niobate (LiNbO 3 8. The method of claim 7, wherein the silicon dioxide comprises silicon carbide (SiCN), silicon carbonitride (SiCN), or a combination thereof.

13. The method of claim 7 , wherein the resist material is deposited via inkjet printing or spin coating.

14. disposing a resist material on the patterned hard mask, the patterned hard mask being disposed over a device material or a substrate, the resist material being disposed over areas of the device material or the substrate corresponding to a grating of a structure to be formed having a depth profile; imprinting a stamp into the resist material over the area, the stamp having a positive pattern of the depth profile, wherein imprinting the stamp and hardening the resist material forms patterned resist over the area; Releasing the stamp; and etching the patterned resist and one of the device material or the substrate to form a grating of a structure having the depth profile in the device material or the substrate.

15. the grating includes a first grating and a second grating; the first depth profile of the first grating is linear, non-linear, or uniform; The method of claim 14 , wherein the second depth distribution of the second grating is linear, non-linear, or uniform.

16. The method of claim 15 , wherein the first depth profile and the second depth profile are different from each other.

17. 15. The method of claim 14, wherein the imprint portion of the stamp has a portion width of about 100 μm to about 100 cm, such that the grating has a grating width of about 100 μm to about 100 cm.

18. The substrate may be silicon (Si), silicon dioxide (SiO 2 ), silicon carbide (SiC), fused silica, diamond, quartz nitride, titanium, niobium, lanthanum, zirconium, yttrium, or a combination thereof.

19. The device materials include silicon carbide (SiC), silicon oxycarbide (SiOC), titanium dioxide (TiO 2 ), silicon dioxide (SiO 2 ), vanadium(IV) oxide (VO x ), aluminum oxide (Al 2 O 3 ), aluminum-doped zinc oxide (AZO), indium tin oxide (ITO), tin dioxide (SnO 2 ), zinc oxide (ZnO), tantalum pentoxide (Ta 2 O 5 ), silicon nitride (Si 3 N 4 ), zirconium dioxide (ZrO 2 ), niobium oxide (Nb 2 O 5 ), cadmium stannate (Cd 2 SnO 4 ), silicon mononitride (SiN), silicon oxynitride (SiON), barium titanate (BaTiO 3 ), diamond-like carbon (DLC), hafnium(IV) oxide (HfO 2 ), lithium niobate (LiNbO 3 ), silicon carbonitride (SiCN), or a combination thereof.

20. 15. The method of claim 14, wherein the patterned hard mask exposes the device material or the substrate.

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