In this paper

diffraction efficiency of SiO2 gratings was calculated based on the rigorous coupled-wave analysis

with normal incidence of a 13.4 nm(92.5 eV) EUV light on a grating of 140 nm period.It was found that the maximal first order diffraction efficiency of the SiO2 grating was much higher than the Si grating

and higher than the Cr/Si3N4 compound gratings currently used at PSI.A new method

which combines advanced silicon etching with silicon oxidation technology

was employed to make the SiO2 nano-grating with high aspect ratio.This method

for making the beam splitter grating especially

solves the problem of direct SiO2 etching and will be used for the soft X-ray interference lithography endstation at SSRF.