Gray-tone lithography for precise control of grating etch depth

US11709422B2 · kind B2 · utility

Assignee

• Meta Platforms Technologies, LLC · US

Inventors

• Elliott Franke · Albany, US
• Nihar Mohanty · Clifton Park, US
• Ankit Vora · San Jose, US
• Austin Lane · Redmond, US
• Matthew E. Colburn · Hopewell Junction, US

Key dates

• Filing date: Sep 17, 2020
• Grant date: Jul 25, 2023
• Expiry date: Jul 2, 2041

Classification

• Technology area (CPC G): Physics
• CPC primary: G02B2027/0178
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

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.