光刻对准中干涉条纹相位解析研究

针对光刻对准中双光栅产生的具有多频率的干涉条纹,提出了一种基于二维解析小波变换进行条纹分析的方法。该方法首先通过二维小波变换的多尺度对条纹的多频率进行分析,并通过解析小波基函数将条纹的幅度与相位进行分离,最终通过二维小波脊方法提取出与偏移量相关的相位。在相位提取的同时通过二维小波脊所处点的角度分布来移除封闭条纹处理中常见的相位符号不确定性。数值模拟与实验验证了该方法的可行性并与传统的基于频域的相位分析方法进行了对比分析。结果表明,该方法能在获得所需相位信息的同时较好地滤除掉由光路抖动引起的噪声,具有很强的适应性。

Interference Fringe Pattern Phase Analysis in Alignment of Nanolithography

The fringe pattern analysis method based on the two-dimensional (2D) analytic wavelet transform (AWT) is proposed for the interference fringe pattern with multi-frequency that occurs in two grating marks in alignment of nanolithography. The multi-frequency of fringe is analysed by the multi-scale of the 2D wavelet transform (WT) first. The separation of the amplitude and phase is processed by the analytic wavelet basis function. The phase correlating to the offset is extracted through the 2D wavelet ridge method finally. The sign ambiguities which always occur in the process of analyzing closed fringe pattern are removed through the discontinuities of the angel in the 2D wavelet ridge. The feasibility of the method is verified by numerical simulation and experiment, and the comparisons of the traditional frequency-based phase analysis method are given. The results show that the noises brought by the fluctuation in the optical path in the fringes can be filtered effectively at the course of acquiring the phase information through the method with good adaptability.