Recent CD AFM probe developments for sub-45 nm technology nodes

Bernard Haochih Liu, Jason R. Osborne, Gregory A. Dahlen, Johann Greschner, Thomas Bayer, Samuel Kalt, Georg Fritz

Research output: Chapter in Book/Report/Conference proceedingConference contribution

10 Citations (Scopus)

Abstract

This paper reports on new developments of advanced CD AFM probes after the prior introduction of "trident probes" in SPIE Advanced Lithography 2007 [1]. Trident probes, having sharpened extensions in the tip apex region, make possible bottom CD measurements within a few nanometers of the feature bottom corner; an area where other CD probes have difficulties due to tip shape limitations. Moreover, new metrology applications of trident probes have been developed for novel devices such as FinFET and vertical read/write hard disk heads. For ever smaller technology nodes, new probes evolved from the design of the trident probe. For example, the number of sharpened tip flares was reduced from three (trident) to two (bi-pod) to prevent possible interference of the third leg in the slow scan direction, as shown in Figure 3. Maintaining tip lateral stiffness as the tip size shrinks to less than 30 nm is vital for successful scanning. Consequently, a significant recent improvement is the change of probe shank cross-sectional geometry in order to maintain tip vertical aspect ratio of 1:5 (and lateral stiffness > 1 N/m). Finally, modifications of probe substrate are proposed and evaluated for current and new CD AFM systems. Hydrophobic, self-assembled monolayer (SAM) coatings were applied on CD probes to reduced tip "pull-away" distance1 during CD AFM scanning. Test results show that the pull away distance can be reduced more than 5 times on average (in some cases, by a factor of 15). Consequently, use of hydrophobic SAM coatings on CD probes mitigates pull-away distance thus allowing narrow trench CD measurements. We discuss limitations of prior CD AFM probes and design considerations of new CD probes. The characterization of first prototypes and evaluation of scan performance are presented in this work.

Original languageEnglish
Title of host publicationMetrology, Inspection, and Process Control for Microlithography XXII
DOIs
Publication statusPublished - 2008 Dec 1
EventMetrology, Inspection, and Process Control for Microlithography XXII - San Jose, CA, United States
Duration: 2008 Feb 252008 Feb 28

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume6922
ISSN (Print)0277-786X

Other

OtherMetrology, Inspection, and Process Control for Microlithography XXII
CountryUnited States
CitySan Jose, CA
Period08-02-2508-02-28

All Science Journal Classification (ASJC) codes

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

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  • Cite this

    Liu, B. H., Osborne, J. R., Dahlen, G. A., Greschner, J., Bayer, T., Kalt, S., & Fritz, G. (2008). Recent CD AFM probe developments for sub-45 nm technology nodes. In Metrology, Inspection, and Process Control for Microlithography XXII [69222J] (Proceedings of SPIE - The International Society for Optical Engineering; Vol. 6922). https://doi.org/10.1117/12.773057