白光干涉测量系统的测量不确定度评定

Evaluation of Uncertainty in Measurement with White-light Interference System

白光干涉测量系统(white-light interference system,WLIS)广泛用于微纳米表面形貌的精密测量,其测量不确定度评定是研究白光干涉测量系统计量特性的一项重要工作。基于微纳米线间隔和台阶,建立了WLIS测量表面形貌时的测量模型,明确了测量不确定度来源;以5000 nm的线间隔和180 nm的台阶高度为例,利用WLIS进行了测量,并分析WLIS的测量重复性、光学组件特性、传感器特性、运动模块性能、测试方法及环境等因素产生的不确定度分量,最终评定该WLIS测量线间隔和台阶高度的合成测量不确定度分别为21 nm和0.4 nm。对WLIS的不确定度评定确保了其测量结果的准确性、溯源性,并提出了提高系统整体计量特性的途径。

White-light interference system(WLIS)is widely used in the measurement of micro-nano surface morpography.The evaluation of measurement uncertainty is an important work to study the metrological characteristics of WLIS.The measurement models of pitch and step height by WLIS were built and the sources of uncertainty were determined.A 50×objective lens was used to measure a pitch standard and a step height standard,which nominal values are 5000 nm and 180 nm respectively.By analyzing the measurement repeatability,optical component quality,sensor parameters,motion module performance,test method and environment of WLIS,the combined measurement uncertainty of pitch and step height measurement are evaluated as 21 nm and 0.4 nm.The uncertainty analysis of WLIS ensures the accuracy and traceability of the measurement results,therefore,provides necessary references for dissemination of the nano-micro dimensional values by WLIS.