3D-AFM tip to tip variations and impact on measurement performances

Foucher, A.-L.; Foucher, J.; Dourthe, L.

doi:10.1117/12.846731

Cited by 3 publications

(1 citation statement)

References 10 publications

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“…For example, Foucher, et al first reported observations indicating that the lateral stiffness of a tip could affect the consistency of the tip calibration using a type of sample known as a vertical parallel structure (VPS). [8] This was a surprising observation since it seems to indicate a breakdown in the assumption that for given instrument parameters there is fixed offset between the geometrical tip width and the effective tip width. In practical application terms, their results indicated the presence of a non-geometrical tip contribution that did not completely cancel when performing a tip calibration and subsequent measurement.…”

Section: Introductionmentioning

confidence: 99%

Lateral tip control effects in CD-AFM metrology: the large tip limit

2015

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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 piezo actuator to position the tip in a manner that resembles touch-triggering of coordinate measuring machine (CMM) 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 nm 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 validate 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 approximately 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.

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Section: Introductionmentioning

confidence: 99%