N rich <i>a</i>-SiN<i>x</i>:H as a prospective material for EUV/soft x-ray mirror: A soft x-ray reflectivity analysis near Si L2,3 absorption edge

Abstract

We report the effect of the stoichiometry (from Si-rich to N-rich) of PECVD-grown a-SiNx:H thin films on their optical properties in the soft x-ray regime. The stoichiometry (x = [N]/[Si]) of thin films varied from 0.25 to 1.48 with the control of the flow of precursor gases. The soft x-ray reflectivity was performed in the vicinity of the Si L2,3 absorption edge energy region to evaluate the soft x-ray optical behavior of these non-stoichiometric thin films. Reflectivity analysis suggests the possible tunability of optical constants of a-SiNx:H thin films with stoichiometry. N-rich a-SiNx:H shows promising optical constant values comparable to widely used SiC for the application of soft x-ray/extreme ultraviolet (EUV) mirrors and for masks in next-generation EUV-based 13.5 nm lithography technology.