Scanning beam interference lithography (SBIL) is an advanced technology developed for manufacturing large-area diffraction grating at a nanometer-scale phase accuracy. To withstand environmental disturbances and maintain the interference fringes still relative to the substrate, SBIL requires high-precision phase control. We proposed a fringe phase control system with homodyne detection for SBIL. First, a homodyne detector is employed to achieve high-precision phase measurement, while ensuring the simplicity of the optics and high laser utilization. The time-varying nonlinear error in the measurement results is corrected by a dynamic ellipse fitting method. To reduce the latency effect, a lead controller is designed using the root locus method based on the model identification result. The lead controller considerably increases the control bandwidth while ensuring a sufficient phase margin, which further suppresses disturbances and stabilizes the interference fringes to within ∼1 / 60 of the fringe period. Wide-range phase tracking for perpendicular scanning with high accuracy is also verified through an experiment.

中文翻译：

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扫描束干涉光刻条纹相位控制系统的分析与设计

扫描束干涉光刻 (SBIL) 是一种先进的技术，用于制造纳米级相位精度的大面积衍射光栅。为了承受环境干扰并保持相对于基板的干涉条纹，SBIL 需要高精度的相位控制。我们提出了一种用于 SBIL 的零差检测条纹相位控制系统。首先，采用零差探测器实现高精度相位测量，同时保证光学器件的简单性和激光的高利用率。测量结果中随时间变化的非线性误差通过动态椭圆拟合方法进行校正。为了减少延迟效应，基于模型识别结果，使用根轨迹法设计了一个前导控制器。超前控制器在确保足够的相位裕度的同时显着增加了控制带宽，这进一步抑制了干扰并将干涉条纹稳定在条纹周期的 1 / 60 以内。还通过实验验证了用于高精度垂直扫描的大范围相位跟踪。