Meta Platforms Technologies, LLC

Facebook Technologies, LLC

Elliott Franke

Matthew E Colburn

Ankit Vora

Austin Lane

Nihar Ranjan Mohanty

Hee Yoon Lee

Yu Shi

Gray-tone lithography techniques for controlling the thickness profile of an overcoat layer on a surface-relief grating that has a non-uniform grating parameter (e.g., depth, duty cycle, or period), compensating for the non-uniform etch rate in a large area, defining etch/block regions, and/or controlling the thickness of the grating layer.

Gray-tone lithography for precise control of grating etch depth

A waveguide display includes a waveguide, an input coupler configured to couple display light into the waveguide, and a surface-relief grating on the waveguide and configured to couple the display light out of the waveguide towards an eyebox of the waveguide display on a first side of the waveguide. The surface-relief grating is formed in a plurality of grating layers having uniform or non-uniform thickness profiles. The plurality of grating layers is characterized by a refractive index modulation that increases and then decreases as the distance of the grating layer from the waveguide increases.

Gradient refractive index grating for display leakage reduction

Disclosed herein are techniques for fabricating straight or slanted variable-etch-depth gratings. A photoresist material for fabricating a variable-etch-depth grating in a substrate is sensitive to light with a wavelength shorter than 300 nm and has an etch rate comparable to the etch rate of the substrate. A depth of an exposed portion of a photoresist material layer including the photoresist material correlates with the exposure dose. After exposure using a gray-scale mask and development, the photoresist material layer has a non-uniform thickness. The photoresist material layer with the non-uniform thickness and the underlying substrate are etched using a straight etching or slanted etching process to form the straight or slanted variable-etch-depth grating in the substrate. The variable-etch-depth grating is characterized by a non-uniform depth profile corresponding to the non-uniform thickness of the photoresist material layer before etching.

Variable-etch-depth gratings

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Bellevue, WA, United States of America

Elliott Franke