Reactive ion beam etch of slanted gratings for augmented reality

Vincent Ip; Frederick Pearsall; Tania Henry; Riju Singhal

doi:10.1117/12.2582752

22 February 2021 Reactive ion beam etch of slanted gratings for augmented reality

Vincent Ip, Frederick Pearsall, Tania Henry, Riju Singhal

Proceedings Volume 11615, Advanced Etch Technology and Process Integration for Nanopatterning X; 116150H (2021) https://doi.org/10.1117/12.2582752
Event: SPIE Advanced Lithography, 2021, Online Only

Abstract

Slanted gratings show high efficiency in coupling light into waveguides, which is critical for optics such as the diffractive optical elements (DOEs) used in augmented reality glasses. Fabrication of master molds used for producing slanted gratings require high etch selectivity between SiO₂ and a metal mask. The industry standard for trench etch, Reactive Ion Etch (RIE), cannot produce slanted trenches. In this work, we demonstrate the fabrication of surface relief grating (SRG) master molds with slant angles of 30, 45 and 60 degrees. Using Reactive Ion Beam Etch (RIBE), etch anisotropy is controlled via the directionality of the ion beam, combined with angle of incidence. The selectivity between metal mask vs SiO₂ can be tuned (7:1 to 12:1). An in-house oxygen cleaning increases stability, leading to high repeatability in process and etch rates. High static uniformity across the wafer surface was achieved using a proprietary tunable ion source.

Conference Presentation

Citation Download Citation

Vincent Ip, Frederick Pearsall, Tania Henry, and Riju Singhal "Reactive ion beam etch of slanted gratings for augmented reality", Proc. SPIE 11615, Advanced Etch Technology and Process Integration for Nanopatterning X, 116150H (22 February 2021); https://doi.org/10.1117/12.2582752

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