Study of the optical response of Si-rich a-SiNx : H thin film near Si L2,3-edge using soft x-ray reflectivity

Abstract

Angle-dependent soft x-ray reflectivity measurements in the photon energy range 82.67–248 eV near the Si L2,3 absorption edge have been performed on Si-rich a-SiNx : H (SRSN) thin film deposited by the Hg-sensitized photo-chemical vapour deposition technique. It is found that experimentally obtained δ (dispersion) values of the SRSN film lie in between that of pure silicon (Si) and silicon nitride (Si3N4). X-ray photoelectron spectroscopy measurements suggest that excess silicon is responsible for reducing optical constants values and hence by controlling the silicon amount one can tune the optical constants to desired values. We further compare the soft x-ray optical spectrum of the SRSN film with those of other silicon compounds such as silicon carbide (SiC) and silicon monoxide (SiO) near the Si L2,3 edge region to shows its possibility as a prospective material for the next generation 13.5 nm (91.85 eV) node extreme ultraviolet (EUV) lithography technology.