Semiconductor Wafer Flatness and Thickness Measurement Using Frequency Scanning Interferometry Technology

作者：Weisheng Cheng, Zexiao Li, Xuanzong Wu, Shuangxiong Yin, Bo Zhang, Xiaodong Zhang · 发表于：Photonics · 年份：2025 · DOI：10.3390/photonics12070663 · 被引用次数：9 · 研究领域：Optical measurement and interference techniques、Integrated Circuits and Semiconductor Failure Analysis、Advanced Surface Polishing Techniques

Silicon (Si) and silicon carbide (SiC) are second- and third-generation semiconductor materials with excellent properties that are particularly suitable for applications in scenarios such as high temperature, high voltage, and high frequency. Si/SiC wafers face warpage and bending problems during production, which can seriously affect subsequent processing. Fast, accurate, and comprehensive detection of thickness, thickness variation, and flatness (including bow and warpage) of SiC and Si wafers is an industry-recognized challenge. Frequency scanning interferometry (FSI) can synchronize the upper and lower surfaces and thickness information of transparent parallel thin wafers, but it is still affected by multiple interfacial harmonic reflections, reflectivity asymmetry, and phase modulation uncertainty when measuring SiC thin wafers, which leads to thickness calculation errors and face reconstruction deviations. To this end, this paper proposes a high-precision facet reconstruction method for SiC/Si structures, which combines harmonic spectral domain decomposition, refractive index gradient constraints, and partitioning optimization strategy, and introduces interferometric signal “oversampling” and weighted fusion of multiple sets of data to effectively suppress higher-order harmonic interferences, and to enhance the accuracy of phase resolution. The multi-layer iterative optimization model further enhances the measurement accuracy and robustness of the system. The flatness m...