Search

EP-3959547-B1 - TRANSFERRING NANOSTRUCTURES FROM WAFERS TO TRANSPARENT SUBSTRATES

EP3959547B1EP 3959547 B1EP3959547 B1EP 3959547B1EP-3959547-B1

Inventors

  • ROY, Tapashree
  • MEYER TIMMERMAN THIJSSEN, Rutger

Dates

Publication Date
20260513
Application Date
20200224

Claims (15)

  1. A method (100) of forming an optical device (200), comprising: Depositing an oxide layer (204) on a first surface of a substrate (202); forming an opening (212) in the oxide layer to expose a portion of the first surface (214) of the substrate; depositing a structure layer (208) on a transparent layer (206), the transparent layer being disposed on a second surface (216) of the substrate opposite the first surface; forming a plurality of nanostructures (210) in the structure layer; etching a portion (220) of the substrate extending from the opening in the oxide layer to the transparent layer; and detaching a portion of the transparent layer having the plurality of nanostructures disposed thereon from the substrate to form an optical device.
  2. The method of claim 1, wherein the transparent layer (206) is deposited on the second surface (216) of the substrate prior to depositing the structure layer (208), and wherein the plurality of nanostructures (210) are formed using a nanoimprint stamp or a lithography process.
  3. The method of claim 1, further comprising providing the substrate (202) having the transparent layer (206) disposed on the second surface as a base prior to depositing the oxide layer (204).
  4. The method of claim 1, wherein the structure layer (208) comprises a material having a refractive index greater than about 1.8 and an absorption coefficient less than about 0.001.
  5. The method of claim 1, wherein the structure layer (208) comprises a material selected from the group consisting of titanium dioxide, gallium phosphide, gallium nitride, zinc oxide, tin dioxide, aluminum-doped zinc oxide, crystalline silicon, and silicon nitride.
  6. The method of claim 1, wherein the substrate (202) comprises silicon, and wherein the transparent layer comprises an oxide material.
  7. The method of claim 1, wherein the portion of the substrate extending from the opening (212) in the oxide layer to the transparent layer (206) is etched using an etchant comprising xenon difluoride.
  8. The method of claim 1, wherein the substrate (202) comprises silicon, the transparent layer (206) comprises silicon dioxide, and the portion of the substrate extending from the opening in the oxide layer to the transparent layer is etched using an etchant having a high selectivity to etch silicon compared to silicon dioxide.
  9. The method of claim 1, wherein the substrate (202) is provided as a base, the substrate comprises silicon and wherein the transparent layer is deposited on the second surface of the substrate; the structure layer comprising a material having a refractive index greater than about 1.8 and an absorption coefficient less than about 0.001.
  10. The method of claim 9, wherein the structure layer (208) comprises a material selected from the group consisting of titanium dioxide, gallium phosphide, gallium nitride, zinc oxide, tin dioxide, aluminum-doped zinc oxide, crystalline silicon, and silicon nitride.
  11. The method of claim 9, wherein the transparent layer (206) comprises an oxide material, and wherein the portion of the substrate extending from the opening in the oxide layer to the transparent layer is etched using an etchant comprising xenon difluoride.
  12. The method of claim 1, further comprising providing a silicon on insulator substrate (650) as a base, wherein the substrate (202) is a silicon containing substrate (602) of the silicon on insulator substrate (650), the structure layer (208) is a silicon containing layer (632) of the silicon on insulator substrate (650), and the transparent layer (206) is a transparent layer (606) of the silicon on insulator substrate (650).
  13. The method of claim 12, wherein the transparent layer (606) comprises an oxide material, or wherein the portion of the silicon containing substrate extending from the opening in the oxide layer (604) to the transparent layer is etched using an etchant comprising xenon difluoride.
  14. The method of claim 12, the transparent layer (606) comprises silicon dioxide, and the portion of the silicon containing substrate extending from the opening in the oxide layer (604) to the transparent layer is etched using an etchant having a high selectivity to etch silicon compared to silicon dioxide.
  15. The method of claim 12, wherein the plurality of nanostructures (610) are formed using a nanoimprint stamp or a lithography process, and wherein the silicon containing layer is selected from a group consisting of crystalline silicon, silicon nitride, and amorphous silicon.

Description

BACKGROUND Field Embodiments of the present disclosure relate to methods of forming optical devices comprising nanostructures disposed on transparent substrates. Description of the Related Art Optical systems may be used to manipulate the propagation of light by spatially varying structural parameters of the structures (e.g., shape, size, orientation) of the optical devices formed on a substrate. The optical devices provide a spatially varying optical response that molds optical wavefronts as desired. These optical devices alter light propagation by inducing localized phase discontinuities (i.e., abrupt changes of phase over a distance smaller than the wavelength of the light). Such optical devices may be composed of different types of materials, shapes, or configurations on the substrate and may operate based upon different physical principles. Flat optical devices in the visible and near-infrared spectrum typically require transparent substrates having nanostructures disposed thereon. However, processing transparent substrates to form optical devices is both complex and expensive. For example, transparent substrates are generally considered to be challenging base substrates or structures for forming nanostructures on, as nanostructures with different materials, profiles, and configurations are often required in an attempt to meet different device performances for the optical devices. It is difficult to form nanoscale structures on transparent substrates having the desired profile cost-effectively while maintaining maximum optical performance and properties suitable of the intended optical devices. US 2018/228410 A1 relates to a process for fabricating a set of guided-mode resonance filters. The fabrication process comprises depositing SiO2, α-Si, TiO2, and Ge on a double polished wafer (Si substrate). The Ge deposition layer is used as grating thin film material, and the α-Si deposition layer is used as waveguide thin film material to form an optical waveguide. A grating structure is patterned on the Ge layer using photolithography. The Ge layer is etched. A grating period can be 9 µm. The SiO2 layer serves as a stop layer when etching away some or all of the Si substrate. WO 2019/043570 A1 relates to a single crystalline diamond optical element production method including the steps of providing a single crystalline diamond substrate, applying a mask layer to the single crystalline diamond substrate, forming at least one or a plurality of indentations or recesses through the mask layer to expose a portion or portions of the single crystalline diamond substrate, and etching the exposed portion or portions of the single crystalline diamond substrate. Optical diamond components comprising grooves of height between 1 µm and 10 µm can be produced. CN 107 390 311 A relates to a surface plasmon resonance grating, and more particularly to a multiple period photonic crystal nanocrack surface plasmon resonance grating. An electron beam lithography method is used for etching a silicon nitride material layer and a gold film layer to generate the nanocracks. Thus, there is a need in the art for methods of forming an optical device comprising nanostructures disposed on a transparent substrate. SUMMARY Embodiments of the present disclosure relate to methods according to independent claim 1. The method of forming an optical device comprises depositing an oxide layer on a first surface of a substrate, forming an opening in the oxide layer to expose a portion of the first surface of the substrate, depositing a structure layer on a transparent layer, the transparent layer being disposed on a second surface of the substrate opposite the first surface, forming a plurality of nanostructures in the structure layer, etching a portion of the substrate extending from the opening in the oxide layer to the transparent layer, and detaching a portion of the transparent layer having the plurality of nanostructures disposed thereon from the substrate to form an optical device. In an embodiment, a method of forming an optical device comprises providing a silicon on insulator substrate as a base, the silicon on insulator substrate comprising a silicon containing substrate, a transparent layer disposed on a first surface of the silicon containing substrate, and a silicon containing layer disposed on the transparent layer, depositing an oxide layer on a second surface of the silicon containing substrate opposite the first surface, forming an opening in the oxide layer to expose a portion of the second surface of the silicon containing substrate, forming a plurality of nanostructures in the silicon containing layer, etching a portion of the silicon containing substrate extending from the opening in the oxide layer to the transparent layer, and detaching a portion of the transparent layer having the plurality of nanostructures disposed thereon from the silicon containing substrate to form an optical device. In another embodiment, a method of