A metrological large range atomic force microscope with improved performance

Area of Science:

• Metrology
• Atomic Force Microscopy
• Nanotechnology

Background:

• The Physikalisch-Technische Bundesanstalt (PTB) has developed and refined a metrological large range atomic force microscope (Met. LR-AFM).
• The instrument utilizes a scanning sample stage with integrated interferometers and a stationary AFM head to adhere to the Abbe measurement principle.

Purpose of the Study:

• To report on further advancements and improvements made to the Met. LR-AFM.
• To enhance the instrument's accuracy, reduce optical interference, and implement versatile scanning capabilities.

Main Methods:

• Development of a new AFM head employing the beam deflection principle to minimize parasitic optical interference.
• Application of an off-line Heydemann correction method to mitigate interferometer nonlinearities, achieving <0.3 nm (p-v).
• Implementation of advanced scanning functions (e.g., radial, local) and software improvements for user-friendly operation.

Main Results:

• Reduced influence of parasitic optical interference phenomena through the new AFM head design.
• Interferometer nonlinearities were corrected to less than 0.3 nm (p-v) using the Heydemann correction.
• Demonstrated capability in measuring geometrical parameters like step height, lateral pitch, line width, and nanoroughness of nanostructures.

Conclusions:

• The improved Met. LR-AFM exhibits excellent metrological performance, validated by calibration results on a 1D grating and film thickness standards.
• The advancements enable precise measurement of various geometrical parameters essential for nanostructure characterization.
• The enhanced instrument provides a versatile and accurate platform for metrological applications in nanotechnology.