The decreasing size of semiconductor features and the increasing structural complexity of advanced devices have placed continuously greater demands on manufacturing metrology, arising both from the measurement challenges of smaller feature sizes and the growing requirement to characterize structures in more than just a single critical dimension. For scanning electron microscopy, this has resulted in increasing sophistication of imaging models. For critical dimension atomic force microscopes (CD-AFMs), this has resulted in the need for smaller and more complex tips. Carbon nanotube (CNT) tips have thus been the focus of much interest and effort by a number of researchers. However, there have been significant issues surrounding both the manufacture and use of CNT tips. Specifically, the growth or attachment of CNTs to AFM cantilevers has been a challenge to the fabrication of CNT tips, and the flexibility and resultant bending artifacts have presented challenges to using CNT tips. The Korea Research Institute for Standards and Science (KRISS) has invested considerable effort in the controlled fabrication of CNT tips and is collaborating with the National Institute of Standards and Technology on the application of CNT tips for CD-AFM. Progress by KRISS on the precise control of CNT orientation, length, and end modification, using manipulation and focused ion beam processes, has allowed us to implement ball-capped CNT tips and bent CNT tips for CD-AFM. Using two different generations of CD-AFM instruments, we have evaluated these tip types by imaging a line/space grating and a programmed line edge roughness specimen. We concluded that these CNTs are capable of scanning the profiles of these structures, including re-entrant sidewalls, but there remain important challenges to address. These challenges include tighter control of tip geometry and careful optimization of scan parameters and algorithms for using CNT tips.

中文翻译：

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临界尺寸原子力显微镜中碳纳米管探针的评估。


半导体特征尺寸的减小和先进器件结构复杂性的增加对制造计量提出了不断更高的要求，这是由于较小特征尺寸的测量挑战以及在多个关键尺寸上表征结构的日益增长的要求。对于扫描电子显微镜来说，这导致成像模型的复杂性不断提高。对于临界尺寸原子力显微镜 (CD-AFM)，这导致需要更小、更复杂的尖端。因此，碳纳米管（CNT）尖端已成为许多研究人员极大兴趣和努力的焦点。然而，碳纳米管尖端的制造和使用都存在重大问题。具体来说，碳纳米管在 AFM 悬臂上的生长或附着一直是碳纳米管尖端制造的挑战，而灵活性和由此产生的弯曲伪影对使用碳纳米管尖端提出了挑战。韩国标准与科学研究所 (KRISS) 在 CNT 尖端的控制制造方面投入了大量精力，并与国家标准与技术研究院合作将 CNT 尖端应用于 CD-AFM。 KRISS 在使用操纵和聚焦离子束工艺精确控制 CNT 方向、长度和末端修饰方面取得的进展，使我们能够实现用于 CD-AFM 的球帽 CNT 尖端和弯曲 CNT 尖端。使用两代不同代的 CD-AFM 仪器，我们通过对线/空间光栅和编程的线边缘粗糙度样本进行成像来评估这些尖端类型。 我们的结论是，这些碳纳米管能够扫描这些结构的轮廓，包括凹进侧壁，但仍然存在需要解决的重要挑战。这些挑战包括更严格地控​​制尖端几何形状以及仔细优化扫描参数和使用 CNT 尖端的算法。