Characterization of Probe Dynamic Behaviors in Critical Dimension Atomic Force Microscopy.

Area of Science:

• Computational Modeling
• Surface Science
• Nanotechnology

Background:

• Atomic Force Microscopy (AFM) is crucial for nanoscale surface characterization.
• Accurate modeling of probe-sample interactions is essential for reliable dimensional measurements.
• Intermittent contact during scanning can introduce significant biases and uncertainties.

Purpose of the Study:

• To develop a detailed computational model for AFM tip-sample interactions.
• To analyze dynamic tip behaviors and estimate deflections caused by intermittent contact.
• To quantify dimensional biases and uncertainties resulting from these interactions.

Main Methods:

• Utilized the finite element method (FEM) to compute probe tip and cantilever beam responses.
• Modeled intermittent contacts with vertical (wall) and horizontal surfaces.
• Employed Lennard-Jones theory to model tip-sample interaction forces for a silicon sample.

Main Results:

• Simulated responses of a 75 nm Critical Dimension (CD) tip in time and frequency domains.
• Calculated snap-in and snap-out dynamics of the probe tip during surface scanning.
• Derived cantilever and probe tip deflections versus interaction forces for vertical and horizontal contacts.

Conclusions:

• The dynamic analysis using FEM and Lennard-Jones models accurately predicts probe-sample interactions.
• The model provides a unique method for calculating tip deflection and the gap between tip and sample.
• Understanding these dynamics is key to improving measurement precision in AFM.