Wei Jiasi, Wu Junjie, Wang Chen
Key Laboratory of Bioanalysis and Metrology for State Market Regulation, Shanghai Institute of Measurement and Testing Technology, Shanghai 201203, China.
Department of Precision Mechanical Engineering, Shanghai University, Shanghai 200444, China.
Sensors (Basel). 2024 Sep 12;24(18):5928. doi: 10.3390/s24185928.
Digital holography has transformative potential for the measurement of stacked-chip microstructures due to its non-invasive, single-shot, full-field characteristics. However, significant light scattering and diffraction at steep edges in step microstructures cause the batwing effect, leading to measurement errors. Herein, we propose a standard-deviation-based adaptive median filter to eliminate batwing effects in step microstructure measurement using digital holography. The standard deviation determines the positions of the steps and the range of the batwing effect. During filtering, the filter window size varies: it adjusts according to the center's position within the batwing effect range and reduces outside this range to prevent distortion in other regions. Filtering weights are set to maintain information integrity while using larger filter windows. Experiments on the Standard Resolution Target USAF 1951 and the standard step height target show that our method successfully eliminates batwings while preserving the integrity of the remaining profile.
数字全息术因其非侵入性、单次拍摄、全场测量的特性，在堆叠芯片微结构测量方面具有变革潜力。然而，阶梯微结构中陡峭边缘处显著的光散射和衍射会导致蝙蝠翼效应，从而产生测量误差。在此，我们提出一种基于标准差的自适应中值滤波器，以消除数字全息术在阶梯微结构测量中的蝙蝠翼效应。标准差决定了阶梯的位置和蝙蝠翼效应的范围。在滤波过程中，滤波器窗口大小会发生变化：它会根据蝙蝠翼效应范围内中心的位置进行调整，并在该范围之外减小，以防止其他区域出现失真。设置滤波权重是为了在使用较大滤波器窗口时保持信息完整性。对美国空军1951标准分辨率靶标和标准阶梯高度靶标的实验表明，我们的方法成功消除了蝙蝠翼效应，同时保留了其余轮廓的完整性。
