Fabrication of blazed diffractive optics by through-mask oxidation

US12287498B2 · kind B2 · utility

Assignee

• Paul Scherrer Institut · CH

Inventors

• Christian David · Lauchringen, DE
• Vitaliy Guzenko · Baden-Baden, DE

Key dates

• Filing date: Aug 11, 2020
• Grant date: Apr 29, 2025
• Expiry date: Mar 14, 2042

Classification

• Technology area (CPC G): Physics
• CPC primary: G03F7/405
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A method for manufacturing a low-angle blazed grating on a semiconductor or silicon substrate, includes spin-coating the substrate with resist layer or hydrogen or polysilsesquioxane, being 100-1000 nm or few hundred nanometers thick, applying grayscale irradiation lithography exposure to the resist layer, generating a dose modulated pattern therein, varying in response to absorbed energy density from irradiation lithography exposure. The coated, irradiated substrate is developed in solution, such as TMAH or NaOH, enabling a blazed profile having structures of thickness-dependent diffusion barriers or SiO2, with 0-1000 nm height to emerge. Thermal oxidation in oxygen atmosphere at elevated temperature with the developed substrate, converts the upper silicon substrate layer into SiO2 to a depth depending on the thickness of the pattern in the resist layer above. Hydrofluoric acid fluid removes the SiO2, creating low-angle low-roughness blazed grating structure on silicon substrate.