Gratings with variable depths formed using planarization for waveguide displays
A manufacturing system performs a deposition of an etch-compatible film over a substrate. The etch-compatible film includes a first surface and a second surface opposite to the first surface. The manufacturing system performs a partial removal of the etch-compatible film to create a surface profile on the first surface with a plurality of depths relative to the substrate. The manufacturing system performs a deposition of a second material over the profile created in the etch-compatible film. The manufacturing system performs a planarization of the second material to obtain a plurality of etch heights of the second material in accordance with the plurality of depths in the profile created in the etch-compatible film. The manufacturing system performs a lithographic patterning of a photoresist deposited over the planarized second material to obtain the plurality of etch heights and one or more duty cycles in the second material.
1. A method comprising:
performing a deposition of an etch-compatible film over a substrate, the etch-compatible film comprising a first surface and a second surface opposite to the first surface;
performing a partial removal of the etch-compatible film to create a surface profile on the first surface with a plurality of different depths relative to the substrate;
performing a deposition of a second material over the profile created in the etch-compatible film;
performing a planarization of the second material to obtain a plurality of different etch heights of the second material in accordance with the plurality of different depths in the profile created in the etch-compatible film; and
performing a lithographic patterning of a photoresist deposited over the planarized second material to obtain the plurality of different etch heights and one or more duty cycles in the second material.
2. The method of claim 1 , wherein the partial removal of the etch-compatible film is based on an etching of the etch-compatible film at one or more locations on the first surface to create the surface profile.
3. The method of claim 1 , wherein the planarization of the second material is based on a chemical mechanical polishing of the second material, the chemical mechanical polishing achieving a target value of thickness and surface roughness of the second material.
4. The method of claim 1 , wherein the etch-compatible film is composed of at least one of: an epoxy resin, a novolac resin, or some combination thereof.
5. The method of claim 1 , wherein the plurality of etch heights is in a range of few hundred nanometers to few microns.
6. The method of claim 1 , wherein the one or more duty cycles is in a range of 10 percent to 90 percent.
7. The method of claim 1 , wherein the etch-compatible film is partially removed to a target thickness in a range of few hundred nanometers to few microns.