提出了一种用X射线反射术标定光谱椭偏仪的方法.作为一种间接测量方法,光谱椭偏术测得的薄膜厚度依赖于其光学常数,不具有可溯源性.在掠入射条件下,X射线反射术能测得薄膜的物理厚度,测量结果具有亚纳米量级的精密度且与薄膜光学常数无关.在单晶硅基底上制备了厚度分别为2nm,18nm,34nm,61nm及170nm的SiO2薄膜标样,并用强制过零点的直线拟合了两种方法的标样测量结果,拟合直线的斜率为1.013±0.013,表明该方法可在薄膜厚度测量中标定光谱椭偏仪. A method of calibrating spectroscopic ellipsometry using X-ray reflectometry is proposed. As an indirect measurement method, the film thickness measured by spectroscopic ellipsometry depends on its optical constants and is not traceable. Under grazing incidence conditions , X-ray reflectometry can measure the physical thickness of the film, the measurement results have sub-nanometer precision and has no relation with the optical constants of the films.A single-crystal silicon substrate is prepared with thicknesses of 2nm, 18nm, 34nm, 61nm and 170nm SiO2 thin film standard samples were prepared and the standard samples of two methods were fitted with the straight line of forced zero crossing. The slope of the fitting straight line was 1.013 ± 0.013, which indicated that the method could calibrate the spectroscopic ellipsometer in the film thickness measurement.