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Technology for fabrication of oxide-based diffractive optical elements

The contribution of the IET to the project was the development of the fabrication technology of diffractive optical elements (DOE) such holographic elements and Fresnel lenses.

Process sequence involves deposition of thin oxide films, photolithography, and etching.

Undoped and intentionally doped oxide layers were deposited by reactive magnetron sputtering from metallic and ceramic targets. Additional thermal processing was used to modify oxide microstructure and composition.

Dry etching processes of oxide-based structures to achieve highly anisotropic etch profiles and smooth side-walls were elaborated. The DOE features were reactive ion etched (RIE) in BCl3/Ar plasma or sputter Ar+-ion etched.

Because of not sufficient selectivity of the photoresist mask during dry etching, appropriate hard metal (Ti, Cr, Ni or Al) or SiO2/metal/SiO2 trilevel masks were developed. The DOE patterns were defined first in the hard mask and next transferred to the oxide-based layers. Finally, the mask was removed with a selective etch revealing the underlying DOE.

The achievements of this project should allow the development of more complex DOEs as well as other oxide-based devices.

Informations connexes

Reported by

Institute of Electron Technology, Dept. of Semiconductor Processing for Photonics
Al. Lotnikow 32/46
02-668 Warsaw
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