On the resolution of subsurface atomic force microscopy and its implications for subsurface feature sizing.

Area of Science:

• Materials Science
• Nanotechnology
• Physics

Background:

• Ultrasound atomic force microscopy (AFM) offers subsurface imaging for nanostructures.
• Imaging contrast arises from local contact stiffness variations caused by subsurface features.
• Existing literature lacks a clear definition of spatial resolution in subsurface AFM.

Purpose of the Study:

• To propose a quantitative approach for assessing spatial resolution in subsurface AFM imaging.
• To investigate the impact of various parameters on lateral resolution for subsurface imaging.
• To understand the relationship between contact stiffness changes and subsurface resolution.

Main Methods:

• Developed a quantitative framework to evaluate lateral resolution in subsurface AFM.
• Analyzed the influence of key parameters on subsurface imaging resolution.
• Utilized threshold criteria, including full width at half maximum and Rayleigh criteria, for feature size quantification.

Main Results:

• Compared simulation results with experimental measurements for subsurface AFM.
• Demonstrated that parameter settings optimal for surface topography AFM are suboptimal for subsurface imaging.
• Quantified the relationship between contact stiffness variations and subsurface resolution.

Conclusions:

• A quantitative method for subsurface AFM resolution assessment has been established.
• Parameter optimization is crucial and differs between surface and subsurface AFM imaging.
• Further understanding of contact mechanics is needed for enhanced subsurface nanostructure imaging.