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US-20260130190-A1 - FORMATION OF ANGLED GRATINGS

US20260130190A1US 20260130190 A1US20260130190 A1US 20260130190A1US-20260130190-A1

Abstract

Systems and methods discussed herein can be used to form gratings at various slant angles across a grating material on a single substrate by determining an ion beam angle and changing the angle of an ion beam among and between ion beam angles to form gratings with varying angles and cross-sectional geometries. The substrate can be rotated around a central axis, and one or more process parameters, such as a duty cycle of the ion beam, can be modulated to form a grating with a depth gradient.

Inventors

  • Rutger MEYER TIMMERMAN THIJSSEN
  • Joseph C. Olson
  • Morgan Evans

Assignees

  • APPLIED MATERIALS, INC.

Dates

Publication Date
20260507
Application Date
20251231

Claims (20)

  1. 1 . A waveguide, comprising: a substrate; and a grating material layer having a top surface and disposed on the substrate, the grating material layer comprising: an input coupling region containing input grating structures disposed in the grating material; an intermediate coupling region containing secondary grating structures disposed in the grating material; and an output coupling region containing output grating structures disposed in the grating material, wherein the output coupling region further comprises: a wedge disposed in the grating material layer, the wedge containing an angled lower surface with a slope; and the output grating structures slant from the angled lower surface of the wedge to the top surface of the grating material at a depth, and each upper surface of the output grating structures is planer to the top surface of the grating material.
  2. 2 . The waveguide of claim 1 , wherein the grating material layer is composed of at least one of titanium oxide, titanium dioxide, vanadium oxide, aluminum oxide, indium tin oxide, zinc oxide, tantalum pentoxide, silicon nitride, titanium nitride, zirconium dioxide, oxynitrides thereof, or any combination thereof.
  3. 3 . The waveguide of claim 1 , wherein the input grating structures comprise a plurality of fins having a coating formed thereon.
  4. 4 . The waveguide of claim 3 , wherein the coating includes one or more layers of an oxide.
  5. 5 . The waveguide of claim 1 , wherein the secondary grating structures comprise a plurality of fins having a coating formed thereon.
  6. 6 . The waveguide of claim 5 , wherein the coating includes one or more layers of an oxide.
  7. 7 . The waveguide of claim 1 , wherein the output grating structures comprise a plurality of fins having a coating formed thereon.
  8. 8 . The waveguide of claim 7 , wherein the coating includes one or more layers of an oxide.
  9. 9 . The waveguide of claim 1 , wherein the depth is from about 10 nm to about 400 nm.
  10. 10 . A waveguide, comprising: a substrate; and a grating material layer disposed on the substrate, the grating material layer comprising: an input coupling region containing input grating structures disposed in the grating material; an intermediate coupling region containing secondary grating structures disposed in the grating material; and an output coupling region containing output grating structures disposed in the grating material, wherein the output coupling region further comprises: a wedge disposed in the grating material layer and the substrate, the wedge containing an angled upper surface with a slope in the grating material layer and a planar lower surface in the substrate; and the output grating structures slant from the planar lower surface in the substrate to the angled upper surface in the grating material layer at a depth.
  11. 11 . The waveguide of claim 1 , wherein the input grating structures comprise a plurality of fins having a coating formed thereon.
  12. 12 . The waveguide of claim 11 , wherein the coating includes one or more layers of an oxide.
  13. 13 . The waveguide of claim 1 , wherein the secondary grating structures comprise a plurality of fins having a coating formed thereon.
  14. 14 . The waveguide of claim 13 , wherein the coating includes one or more layers of an oxide.
  15. 15 . The waveguide of claim 1 , wherein the output grating structures comprise a plurality of fins having a coating formed thereon.
  16. 16 . The waveguide of claim 15 , wherein the coating includes one or more layers of an oxide.
  17. 17 . A waveguide, comprising: a substrate; and a grating material layer having a top surface and disposed on the substrate, the grating material layer comprising: an input coupling region containing input grating structures disposed in the grating material; an intermediate coupling region containing secondary grating structures disposed in the grating material, wherein the intermediate coupling region further comprises: a first wedge disposed in the grating material layer, the first wedge containing a first angled lower surface with a first slope; and the output grating structures slant from the first angled lower surface of the first wedge to the top surface of the grating material at a first depth, and each upper surface of the output grating structures is planer to the top surface of the grating material; and an output coupling region containing output grating structures disposed in the grating material, wherein the output coupling region further comprises: a second wedge disposed in the grating material layer, the second wedge containing a second angled lower surface with a second slope; and the output grating structures slant from the second angled lower surface of the second wedge to the top surface of the grating material at a second depth, and each upper surface of the output grating structures is planer to the top surface of the grating material.
  18. 18 . The waveguide of claim 17 , wherein the input grating structures comprise a plurality of fins having a coating formed thereon, and wherein the coating includes one or more layers of an oxide.
  19. 19 . The waveguide of claim 17 , wherein the secondary grating structures comprise a plurality of fins having a coating formed thereon, and wherein the coating includes one or more layers of an oxide.
  20. 20 . The waveguide of claim 17 , wherein the output grating structures comprise a plurality of fins having a coating formed thereon, and wherein the coating includes one or more layers of an oxide.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. application Ser. No. 17/832,570, filed Jun. 3, 2022, which is a continuation of U.S. application Ser. No. 16/656,798, filed Oct. 18, 2019, now U.S. Pat. No. 11,380,578, which claims benefit to U.S. Prov. Appl. No. 62/756,970, filed on Nov. 7, 2018, which are herein incorporated by reference in their entirety. BACKGROUND Field Embodiments of the present disclosure generally relate to angled etch tools. More specifically, embodiments described herein provide for utilizing angled etch tools to form gratings with different slant angles, depth gradients, and wedge angles. Description of the Related Art Augmented reality creates an experience for a user that can be viewed through display lenses of augmented reality glasses or using other HMD devices to view the surrounding environment. Augmented reality devices allow users to see images of virtual objects that are generated for display and appear as part of the environment. Augmented reality can include audio and haptic inputs, as well as virtual images, graphics, and video that enhances or augments the user's environment. One challenge in augmented reality device design and fabrication is the display of a virtual image that is overlaid on an ambient environment. Augmented waveguide combiners are used to assist in overlaying images. Generated light is first in-coupled into an augmented waveguide combiner and propagated through the augmented waveguide combiner. The generated light is then out-coupled from the augmented waveguide combiner and overlaid on the ambient environment. Light is coupled into and out of augmented waveguide combiners using surface relief gratings. The intensity of the out-coupled light may not be adequately controlled using conventional designs. Another challenge is that a waveguide combiner may use gratings with different slant angles depending on the properties desired of the augmented reality device. Additionally, a waveguide combiner may include gratings with different slant angles to adequately control the in-coupling and out-coupling of light, and the slant angles may be at angles different than the grating vector. Accordingly, what is needed is improved augmented waveguides combiners and methods of fabrication of gratings and grating masters. SUMMARY In one or more embodiments, a method of forming a grating includes etching a hardmask layer to form a plurality of openings, the hardmask layer being disposed over a grating material layer that is disposed on a substrate and forming a first grating in the grating material layer through the plurality of openings of the hardmask layer, wherein the first grating has a first shape vector and a first grating vector. The first grating can be formed by determining a first ion beam angle ϑ1 relative to a first slant angle ϑ1′ and an angle φ1 which is between the first shape vector and the first grating vector and positioning a first portion of the grating material layer in a path of an ion beam at the first ion beam angle ϑ1 relative to the substrate, the substrate being retained on a platen. The method also includes modulating one or more process parameters when the ion beam is at the first ion beam angle ϑ1 to form a first plurality of fins of the first grating having the first shape vector, the first grating vector, and the first slant angle ϑ1′ relative to a surface normal of the substrate such that the first plurality of fins are formed at the first slant angle ϑ1′. In some examples, the first grating is further formed by rotating the substrate about a central axis of the platen to a first rotation angle between the ion beam and the first grating vector of the first grating. In some embodiments, a method of forming a grating, including: etching a first grating material layer to form a first feature in the first grating material layer disposed on a substrate, depositing an etch stop layer in the first feature, depositing a second grating material layer on the etch stop layer, and depositing a hardmask layer on the second grating material layer. The method further includes etching the hardmask layer to form a plurality of openings and forming a first grating in the second grating material layer through the plurality of openings, wherein the first grating has a first shape vector and a first grating vector. The first grating can be formed by determining a first ion beam angle ϑ1 relative to a first slant angle ϑ1′ and an angle φ1 which is between the first shape vector and the first grating vector, and by positioning a first portion of the substrate relative to an ion beam at the first ion beam angle ϑ1, the substrate being retained on a platen and the first ion beam angle ϑ1 being measured relative to a plane parallel to the platen. The method also includes modulating one or more process parameters when the ion beam is at the first ion beam angle ϑ1 and in contact with the first portion of the substrate. In some