Atomic force microscopy (AFM) is widely used for nano-dimensional metrology in semiconductor manufacturing and metrological system. However, the conventional AFM can't provide accurate CD characterization of nanostructures, due to its top-down configuration and probe-size effect. In this paper, we develop a dual-probe atomic force microscopy (DPAFM). Compared to conventional optical-lever based AFM, the DPAFM exploits two tuning fork probes that simplifies significantly the setup and can be controlled based on frequency-modulation (FM) mode. The developed DPFAM is implemented that builds a zero-reference point by dual-probe alignment firstly, following which, characterizes nanostructures from two sides independently with the two probes. The final CD feature is determined by matching profiles from the two probes based on the zero-reference point. The capability of the DPAFM is validated by experiments on a CD-standard structure, that achieves the true CD assessment with good accuracy and repeatability.

中文翻译：

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基于音叉探针的双探针原子力显微镜用于临界尺寸计量

原子力显微镜（AFM）广泛用于半导体制造和计量系统中的纳米尺寸计量。然而，由于其自​​上而下的配置和探针尺寸效应，传统的 AFM 无法提供纳米结构的准确 CD 表征。在本文中，我们开发了一种双探针原子力显微镜 (DPAFM)。与传统的基于光学杠杆的 AFM 相比，DPAFM 利用两个音叉探头，大大简化了设置，并且可以基于频率调制 (FM) 模式进行控制。所开发的 DPFAM 首先通过双探针对准建立零参考点，然后用两个探针独立地从两侧表征纳米结构。最终的 CD 特征是通过基于零参考点匹配来自两个探头的轮廓来确定的。DPAFM 的能力通过对 CD 标准结构的实验进行验证，该结构以良好的准确性和可重复性实现了真正的 CD 评估。