Share Email Print
cover

Journal of Micro/Nanolithography, MEMS, and MOEMS

Lateral tip control effects in critical dimension atomic force microscope metrology: the large tip limit
Author(s): Ronald G. Dixson; Ndubuisi G. Orji; Ryan S. Goldband
Format Member Price Non-Member Price
PDF $20.00 $25.00

Paper Abstract

Sidewall sensing in critical dimension atomic force microscopes (CD-AFMs) usually involves continuous lateral dithering of the tip or the use of a control algorithm and fast response piezoactuator to position the tip in a manner that resembles touch-triggering of coordinate measuring machine probes. All methods of tip position control, however, induce an effective tip width that may deviate from the actual geometrical tip width. Understanding the influence and dependence of the effective tip width on the dither settings and lateral stiffness of the tip can improve the measurement accuracy and uncertainty estimation for CD-AFM measurements. Since CD-AFM typically uses tips that range from 15 to 850 nm in geometrical width, the behavior of effective tip width throughout this range should be understood. The National Institute of Standards and Technology (NIST) has been investigating the dependence of effective tip width on the dither settings and lateral stiffness of the tip, as well as the possibility of material effects due to sample composition. For tip widths of 130 nm and lower, which also have lower lateral stiffness, the response of the effective tip width to lateral dither is greater than for larger tips. However, we have concluded that these effects will not generally result in a residual bias, provided that the tip calibration and sample measurement are performed under the same conditions. To confirm that our prior conclusions about the dependence of effective tip width on lateral stiffness are valid for large CD tips, we recently performed experiments using a very large non-CD tip with an etched plateau of ∼2-μm width. The effective lateral stiffness of these tips is at least 20 times greater than typical CD-AFM tips, and these results supported our prior conclusions about the expected behavior for larger tips. The bottom-line importance of these latest observations is that we can now reasonably conclude that a dither slope of 3  nm/V is the baseline response due to the induced motion of the cantilever base.

Paper Details

Date Published: 25 January 2016
PDF: 6 pages
J. Micro/Nanolith. 15(1) 014003 doi: 10.1117/1.JMM.15.1.014003
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 15, Issue 1
Show Author Affiliations
Ronald G. Dixson, National Institute of Standards and Technology (United States)
Ndubuisi G. Orji, National Institute of Standards and Technology (United States)
Ryan S. Goldband, Binghamton Univ. (United States)


© SPIE. Terms of Use
Back to Top