Super-high aspect ratio diffractive optics fabricated by batch-processing

Abstract

A batch processing method for fabrication of diffractive optics is disclosed, having applicability to high resolution ultra-high aspect ratio Fresnel Zone Plates for focusing of X-rays or gamma-rays having energies up to hundreds of keV. An array of precursor forms comprising columns is etched into a planar substrate. After sidewall smoothing, a nanolaminate, comprising a sequence of alternating layers of different complex refractive index, is deposited on the sidewall of each column by atomic layer deposition (ALD), to define a specified diffractive line pattern around each column, to form a binary or higher order diffractive optic. After front surface planarization and thinning of the substrate to expose first and second surfaces of the diffractive line pattern of each diffractive optic, the height h in the propagation direction provides a designed absorption difference and/or phase shift difference between adjacent diffractive lines. Optionally, post-processing enhances mechanical, thermal, electrical and optical properties.