Effect of tip shape on line edge roughness measurement based on atomic force microscopy

Area of Science:

• Materials Science
• Metrology
• Nanotechnology

Background:

• Atomic force microscopy (AFM) is crucial for precise line edge roughness (LER) measurements in semiconductor manufacturing.
• The accuracy of AFM LER measurements is highly sensitive to the geometry of the AFM tip.
• Understanding tip-sample interactions is essential for reliable nanoscale metrology.

Purpose of the Study:

• To theoretically investigate the influence of AFM tip shape on LER measurement accuracy.
• To develop formulas for quantifying the discrepancy between measured and actual line edges.
• To provide practical guidance for reducing measurement errors stemming from tip shape variations.

Main Methods:

• Theoretical modeling of AFM tip-sample convolution effects on LER.
• Derivation of mathematical formulas to calculate edge position deviations.
• Experimental validation using three distinct AFM tip shapes with varying geometries.
• Comparative analysis of measurement results obtained with different tips.

Main Results:

• Tip shape introduces a measurable distance between the actual and identified line edge.
• Different tip geometries result in quantitatively different LER measurement errors.
• The study quantifies the impact of tip apex angle and curvature on measurement fidelity.
• Experimental data confirms the theoretical predictions regarding tip shape influence.

Conclusions:

• AFM tip shape is a critical parameter that must be considered for accurate LER assessment.
• Implementing the derived formulas can help correct for tip-induced measurement errors.
• Careful selection and characterization of AFM tips are recommended for high-precision LER metrology.
• This research contributes to improving the reliability of nanoscale dimensional measurements.