Surface topography reconstruction of highly reflective wafers for in-line inspection via deep learning and Fizeau interferometry
摘要
In advanced semiconductor manufacturing, precise surface inspection of silicon wafers is crucial for achieving high yield and reliable device performance. Conventional surface inspection techniques predominantly detect local defects, constraining the evaluation of the global surface topography, an increasingly critical factor as the demand for large-diameter wafers and fine node scales increases. Interferometric metrology, particularly phase-shifting interferometry (PSI), provides nanometer-level precision in full-field surface inspection, but faces practical challenges in in-line environments owing to its sensitivity to environmental instabilities and the requirement for multiple phase-shifted interferometric images. To address these challenges, we propose a novel surface inspection framework that integrates a wavelength-tuning Fizeau interferometer with a novel deep learning-based phase reconstruction model, TridentNet. The framework reconstructs the wafer surface topography using only two arbitrarily phase-shifted interferometric images, significantly reducing acquisition requirements while preserving high reconstruction fidelity. The system comprises three interconnected modules: interferometric image acquisition, deep learning-based surface reconstruction, and quantitative evaluation based on industrial standards. Our method is trained on simulated datasets reflecting practical conditions, such as the phase-shift interval, additive noise, and nonlinear distortions. Extensive simulations and experimental validations confirm the robustness and accuracy of the proposed method compared with those of conventional techniques, achieving low errors (root-mean-square 0.0206λ) and a high repeatability (standard deviation 0.0185λ). The framework generates comprehensive analysis reports, including statistical metrics and conformity assessments, thereby facilitating process traceability and optimization. This methodology enables in-line, full-field metrology for highly reflective, large-diameter wafers, presenting a reliable solution for next-generation semiconductor manufacturing.