Apertures for flat optical devices
Embodiments described herein relate to methods for fabricating optical devices. The methods described herein enable the fabrication of one or more optical devices on a substrate with apertures surrounding each of the optical devices having a plurality of structures. One embodiment of the methods described herein includes disposing an aperture material layer on a surface of a substrate, disposing a structure material layer over the apertures and the surface of the substrate, disposing a hardmask over the apertures and the structure material layer, disposing a patterned photoresist over the hardmask, the patterned photoresist defining exposed hardmask portions, removing the exposed hardmask portions to expose structure portions of the structure material layer, and removing the structure portions to form a plurality of structures between the apertures over regions of the surface of the substrate.
1. A method, comprising:
disposing a structure material layer on a surface of a substrate, wherein the structure material layer is disposed between regions of the surface of the substrate corresponding to:
a first space defined by a first optical device and a second optical device, the first optical device having a first plurality of structures to be formed and the second optical device having a second plurality of structures to be formed; and
a second space defined by the first optical device and the second optical device and a periphery of the substrate;
disposing a hardmask over the structure material layer;
disposing a patterned photoresist corresponding to the pattern of the first plurality of structures and the second plurality of structures over the hardmask, the patterned photoresist defining exposed hardmask portions;
removing the exposed hardmask portions to expose structure portions of the structure material layer;
removing the structure portions to form the first plurality of structures of the first optical device and the second plurality of structures of the second optical device between the regions of the surface of the substrate; and
forming an aperture material over the regions corresponding to the first space and the second space, the aperture material being spaced radially from the first plurality of structures and the second plurality of structures, wherein the aperture material, the first optical device, and the second optical device are positioned above and directly contacting a same horizontal plane across a top surface of the substrate, wherein the first optical device and the second optical device are metasurfaces.
2. The method of claim 1 , wherein the forming the aperture material over the regions comprises:
disposing an encapsulation layer over the first plurality of structures of the first optical device and the second plurality of structures of the second optical device and the regions;
disposing an aperture material layer over the encapsulation layer;
disposing a patterned etch layer over the regions to expose a portion of the aperture material layer over the first plurality of structures of the first optical device and the second plurality of structures of the second optical device;
removing the portion of the aperture material layer over the first plurality of structures of the first optical device and the second plurality of structures of the second optical device; and
removing the patterned etch layer.
3. The method of claim 2 , wherein the encapsulation layer comprises one or more of silicon nitride (Si 3 N 4 ), silicon oxide (SiO 2 ), fluoropolymers, hydrogels, and photoresist containing materials.
4. The method of claim 1 , wherein the forming the aperture material over the regions comprises masking the first plurality of structures of the first optical device and the second plurality of structures of the second optical device to expose the regions.
5. The method of claim 1 , wherein the forming the aperture material over the regions comprises:
disposing a gap fill material over the first plurality of structures of the first optical device and the second plurality of structures of the second optical device between the regions;
disposing an aperture material layer over the gap fill material and the regions;
removing the aperture material layer over the gap fill material; and
removing the gap fill material.
6. The method of claim 1 , wherein the aperture material is formed after removing the structure portions to form the first plurality of structures of the first optical device and the second plurality of structures of the second optical device.
7. The method of claim 1 , wherein the forming the aperture material over the regions comprises:
disposing an encapsulation layer over the first plurality of structures of the first optical device and the second plurality of structures of the second optical device and the regions;
disposing an aperture material layer over the encapsulation layer;
disposing a patterned etch layer over portions of the aperture material layer that are disposed between the regions of the surface of the substrate that correspond to the first space and the second space to expose a portion of the aperture material layer over the first plurality of structures of the first optical device and the second plurality of structures of the second optical device;
removing the portion of the aperture material layer over the first plurality of structures of the first optical device and the second plurality of structures of the second optical device; and
removing the patterned etch layer.
8. The method of claim 1 , wherein the forming the aperture material over the regions comprises:
disposing a gap fill material between the regions of the surface of the substrate that correspond to the first space and the second space to expose the regions;
disposing an aperture material layer over the gap fill material and the regions;
removing the aperture material layer over the gap fill material; and
removing the gap fill material.
9. The method of claim 8 , wherein the gap fill material is removed by a solvent, wet etching, ashing, reactive ion etching (RIE), or combinations thereof.
10. The method of claim 7 , wherein the encapsulation layer is disposed using physical vapor deposition (PVD), chemical vapor deposition (CVD), furnace chemical vapor deposition (FCVD), spin-on coating, or combinations thereof.