Traceable atomic force microscope dimensional metrology at NIST

Ronald Dixson; Ndubuisi G. Orji; Joseph Fu; Michael Cresswell; Rich Allen; Will Guthrie

doi:10.1117/12.656803

24 March 2006 Traceable atomic force microscope dimensional metrology at NIST

Ronald Dixson, Ndubuisi G. Orji, Joseph Fu, Michael Cresswell, Rich Allen, Will Guthrie

Proceedings Volume 6152, Metrology, Inspection, and Process Control for Microlithography XX; 61520P (2006) https://doi.org/10.1117/12.656803
Event: SPIE 31st International Symposium on Advanced Lithography, 2006, San Jose, California, United States

Abstract

The National Institute of Standards and Technology (NIST) has a multifaceted program in atomic force microscope (AFM) dimensional metrology. There are two major instruments being used for traceable AFM measurements at NIST. The first is a custom in-house metrology AFM, called the calibrated AFM (C-AFM), and the second instrument is a commercial critical dimension AFM (CD-AFM). The C-AFM has displacement metrology for all three axes traceable to the 633 nm wavelength of the Iodine-stabilized He-Ne laser. In the current generation of this system, the relative standard uncertainty of pitch and step height measurements is approximately 1.0 x 10^-3 for pitches at the micrometer scale and step heights at the 100 nm scale, as supported by several international comparisons. We expect to surpass this performance level soon. Since the CD-AFM has the capability of measuring vertical sidewalls, it complements the C-AFM. Although it does not have intrinsic traceability, it can be calibrated using standards measured on other instruments - such as the C-AFM, and we have developed uncertainty budgets for pitch, height, and linewidth measurements using this instrument. We use the CD-AFM primarily for linewidth measurements of near-vertical structures. At present, the relative standard uncertainties are approximately 0.2% for pitch measurements and 0.4% for step height measurements. As a result of the NIST single crystal critical dimension reference material (SCCDRM) project, it is possible to calibrate CD-AFM tip width with a 1 nm standard uncertainty. We are now using the CD-AFM to support the next generation of the SCCDRM project. In prototypes, we have observed features with widths as low as 20 nm and having uniformity at the 1 nm level.

Citation Download Citation

Ronald Dixson, Ndubuisi G. Orji, Joseph Fu, Michael Cresswell, Rich Allen, and Will Guthrie "Traceable atomic force microscope dimensional metrology at NIST", Proc. SPIE 6152, Metrology, Inspection, and Process Control for Microlithography XX, 61520P (24 March 2006); https://doi.org/10.1117/12.656803

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