Advanced CD-AFM probe tip shape characterization for metrology accuracy and throughput

Bernard Haochih Liu, Jason R. Osborne, Marc Osborn, Gregory A. Dahlen

研究成果: Conference contribution

18 引文 斯高帕斯(Scopus)


As semiconductor and data storage industries apply Critical Dimension Atomic Force Microscopy (CD-AFM) for their metrology needs in research and production, (1) measurement accuracy/repeatability and (2) measurement throughput are the major criteria for acceptance. However, these two requirements are usually contradictory for a metrology instrument. For example, a scatterometer can take a snapshot of a wafer in seconds, but such indirect CD measurements are biased by the availability of library models and uncertainty of computer simulations. Transmission Electron Microscopy (TEM) provides an atomic-scale resolution that is traceable back to the lattice structure of atoms, yet the cross-section data is highly localized and can take days or weeks to acquire. In the case of CD-AFM, since the scanning probe physically interacts with the structure of interest at a close proximity, the determination of sample morphology comes from direct measurements. Therefore, the measurement uncertainty can be attributed to: (1) AFM probe tip shapes and (2) system control and scan algorithms. For the former, past efforts have been mainly focused on improving metrology accuracy and repeatability by reducing the dimensional uncertainty of a tip shape. This approach includes characterizing the probe tip shape periodically. Inevitably, such tip shape calibration procedure takes time (approximately 5 min) and burdens production throughput. In this paper, we introduce several new methods for AFM probe tip shape characterization with different designs of tip shape characterizers. The new tip shape characterizers were designed to address the limitation of current structures. First, a single silicon overhang structure with wear-resistant coatings was used as the characterizer for both tip width and tip shape profile. Tip-to-tip scan repeatability data (0.7 nm 3 Sigma) and measurement statistics suggest an improvement over present state-of-the-art practice. Tip shape profiles of several high aspect ratio (20:1 to 25:1), low lateral stiffness probes were successfully characterized with this method. Furthermore, the use of single characterizer provides an opportunity to shorten tool calibration time, and consequently, increase measurement throughput. In addition, a carbon nanotube characterizer prototype is proposed for CD-AFM. When scanning probe geometry shrinks with semiconductor technology nodes, it has become a challenge to characterize a probe with a few tens of nanometer of width with a micrometer-size characterizer. Using a comparable or smaller size of characterizer for a small (20 to 50 nm) AFM probe not only reduces the dimensional uncertainty, but also expands the 2-D profiling capability of current tip shape characterization. We will discuss limitations of current tip shape profiling techniques, proof-of-concept experiments for new characterizers, implementation of new tip shape characterization methods, and approaches to increasing measurement throughput.

主出版物標題Metrology, Inspection, and Process Control for Microlithography XXI
版本PART 3
出版狀態Published - 2007 十月 15
事件Metrology, Inspection, and Process Control for Microlithography XXI - San Jose, CA, United States
持續時間: 2007 二月 262007 三月 1


名字Proceedings of SPIE - The International Society for Optical Engineering
號碼PART 3


OtherMetrology, Inspection, and Process Control for Microlithography XXI
國家United States
城市San Jose, CA


All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


Liu, B. H., Osborne, J. R., Osborn, M., & Dahlen, G. A. (2007). Advanced CD-AFM probe tip shape characterization for metrology accuracy and throughput. 於 Metrology, Inspection, and Process Control for Microlithography XXI (PART 3 編輯). [65183K] (Proceedings of SPIE - The International Society for Optical Engineering; 卷 6518, 編號 PART 3).