Lateral Tip Control Effects in CD-AFM Metrology: The Large Tip Limit.

Area of Science:

• Metrology
• Surface Science
• Nanotechnology

Background:

• Critical dimension atomic force microscopy (CD-AFM) is vital for nanoscale measurements.
• Sidewall sensing in CD-AFM relies on tip positioning, which can alter the effective tip width.

Purpose of the Study:

• To investigate how tip dither settings and lateral stiffness affect the effective tip width in CD-AFM.
• To improve measurement accuracy and uncertainty estimation for CD-AFM.

Main Methods:

• The study analyzed the dependence of effective tip width on dither settings and tip lateral stiffness.
• Experiments were conducted using tips ranging from 130 nm down to smaller sizes, and also with a large 2-micrometer tip.

Main Results:

• Smaller tips (≤130 nm) showed a greater response of effective tip width to lateral dither compared to larger tips.
• Experiments with a large, stiff tip validated prior conclusions about effective tip width behavior.
• A baseline response of 3 nm/V was identified due to cantilever base motion.

Conclusions:

• Effective tip width variations due to dither and stiffness do not generally cause residual bias if calibration and measurement conditions match.
• The findings support the accurate application of CD-AFM across a wide range of tip sizes.
• Established calibration procedures are sufficient for reliable CD-AFM measurements.