基于严格的矢量耦合波方法,结合纳米级光栅实际制作工艺,定量分析了在13.4 nm软X射线(TE偏振)正入射条件下,光栅材料、厚度、占空比、梯形浮雕底角大小等因素对光栅一级衍射效率的影响。结果表明,在此波段处,Si3N4、Cr、Au浮雕的相位作用对光栅衍射起重要影响,其中非金属材料Si3N4比金属材料Cr、Au的相位作用更明显。最后优化得到了用Si(或Si3N4)做衬底的Si3N4、Cr、Au光栅,分析结果显示,其一级衍射效率优于目前用于13.4 nm软X射线干涉光刻的Cr、Si3N4复合光栅。

Based on the rigorous coupled-wave analysis, considering the actual fabrication processes for nanometer level gratings, the first-order diffraction efficiency was simulated for a normally-incident transmission grating at wavelength of 13.4 nm. The influence on the first-order diffraction efficiency by parameters, such as grating materials, relief thickness, gap/period ratio, and trapezoidal angle on the relief are analyzed quantitatively. The results show at the wavelength, the phase of the relief (Si3N4, Cr, Au) effects grating diffraction greatly. The phase shift of the nonmetallic relief (Si3N4) is found to precede the metallic materials (Cr, Au). After optimization, Si3N4, Cr and Au gratings with Si (Si3N4) substrate are proposed , which have the higher first-order diffraction efficiency than the Cr/Si3N4 compound gratings currently used for soft X-ray interference lithography.