基于X射线掠射法的纳米薄膜厚度计量与量值溯源研究

为了实现纳米薄膜厚度的高精度计量,研制了可供台阶仪、扫描探针显微镜等接触测量的纳米薄膜样片,研究了X射线掠射法测量该纳米薄膜样片厚度的基本原理和计算方法,导出了基于Kiessig厚度干涉条纹计算膜层厚度的线性拟合公式,并提出了一种可溯源至单晶硅原子晶格间距和角度计量标准的纳米膜厚量值溯源方法,同时给出了相应的不确定度评定方法.实验证明:该纳米薄膜厚度H测量相对扩展不确定度达到U=0.3 nm+1.5%H,包含因子k=2.从而建立了一套纳米薄膜厚度计量方法和溯源体系.

Nanometer film thickness metrology and traceability based on grazing incidence X-ray reflectometry

To realize metrology of the nanometer thin film thickness with high accuracy, a series of the nanometer film thickness standard samples with single layer is developed which could be measured by contact instruments such as stylus contact surface step profiler and scanning probe microscopy. The measurement and calculation method of grazing incidence X-ray reflectometry (GIXRR) for film thickness are studied. The formula of linear fitting method based on the periodic Kiessig fringes for thickness measurement is presented. A tracing approach of film thickness measurement, which is traceable to the atomic lattice of monocrystalline silicon and national angle standard, is proposed, and a new optics calibration method is presented which can measure angular misalignment of GIXRR apparatus. The relative expanded uncertainty of the nanofilm thickness H measurement is U=0.3 nm+1.5%H with coverage factor k=2.
Keywords：nano metrologynanofilm thicknessgrazing incidence X-ray reflectometrythickness metrology