Improved nanostructure reconstruction by performing data refinement in optical scatterometry
Improved nanostructure reconstruction by performing data refinement in optical scatterometry
复制标题
通过在光学散射测量中执行数据细化改进纳米结构重建
DOI：
10.1088/2040-8978/18/1/015605
复制
发表时间：
2016
影响因子：
2.1
通讯作者：
Liu Shiyuan
中科院分区：
文献类型：
--
作者：
Zhu Jinlong;Jiang Hao;Shi Yating;Chen Xiuguo;Zhang Chuanwei;Liu Shiyuan
最近，我们间接地证明了光学散射测量中的离群点会降低纳米结构重建的精度，并且我们已经应用稳健估计方法来抑制这些离群点。然而，可能存在的严重掩蔽效应的存在可能导致测量精度低的风险，因为孤立点的检测简单地基于残差值的判断。本文提出了一种新的直接检测孤立点的方法，该方法可以直观地显示二维坐标系中的孤立点。此外，提出了一种基于最小剪裁平方估计回归原理的稳健校正步骤来代替传统的高斯-牛顿迭代步骤，从而实现了更可靠和更准确的纳米结构重建。通过对一维刻蚀硅栅的改进重建，验证了所提方法的可行性。
Recently, we have indirectly demonstrated that nanostructure reconstruction accuracy is degraded by the outliers in optical scatterometry, and we have applied the robust estimation method to suppress these outliers. However, the existence of a possible heavy masking effect could result in the risk of low measurement accuracy, since the detection of outliers is simply based on the judgment of residual value. In this work, a novel method is introduced to directly detect outliers, which can provide the intuitional display of outliers in a two-dimensional coordinate system. Moreover, a robust correction step based on the principle of least trimmed squared estimator regression is proposed to replace the conventional Gauss–Newton iteration step, by which the more reliable and accurate nanostructure reconstruction is achieved. The improved reconstruction of a one-dimensional etched Si grating has demonstrated the feasibility of the proposed methods.