掠入射X射线散射法测量超光滑表面

Measurement of super-smooth surface by grazing X-ray scattering method

介绍了掠入射X射线散射法(GXRS)测量超光滑表面的原理及基于商业用X射线衍射仪改造而成的实验装置。选择3片不同粗糙度的硅片作为实验样品,根据一级矢量微扰理论对各个样品所测量的散射分布进行处理。结果表明,GXRS法得到的样品功率谱密度函数(PSD)与使用原子力显微镜(AFM)所测量的结果基本相符。分析了探测器接收狭缝的宽度和入射光发散度对实验结果的影响,结果表明,在其他实验条件理想的情况下,当探测器接收狭缝宽度<0.02mm,入射光发散度<43″时,在空间频率>0.03μm-1的范围内,由其引起的PSD函数测量误差<2%。随着探测器接收狭缝宽度和入射光发散度的减小,测量误差呈指数迅速减小。在所测量的空间频率范围内,PSD函数的误差随频率的增加而减小,仪器的重复精度优于2.6%。

This paper introduces the measurement principle of a super-smooth surface by a Grazing X-ray Scattering（GXRS）method and an experimental facility based on an improved X-ray diffractometer.By using three kinds of wafers with different roughnesses as samples,the scattering distribution of the samples are treated by first-order vector perturbation theory.The results indicate that the calculated Power Spectral Density（PSD）by GXRS is in a good agreement with the results obtained from Atomic Force Microscope（AFM）.It also analyzes the effects of the slit width of a detector and the divergence of incidence X-ray on experimental results,results show that when the slit width is 0.02 mm and the incidence divergence is 43″,the errors are both lower than 2% in the range of spatial frequency higher than 0.03 μm-1.It is concluded that the measuring errors decrease quickly with the reduces of the slit width and incidence divergence,and the PSD error also decreases quickly with the increase of spatial frequency.The repeatability of the experimental facility is better than 2.6%.