Is the Ne operation of the helium ion microscope suitable for electron backscatter diffraction sample preparation?

Area of Science:

• Materials Science
• Surface Science
• Analytical Chemistry

Background:

• Electron backscatter diffraction (EBSD) requires a mirror-flat sample surface for accurate analysis.
• Focused ion beam (FIB) polishing is a common method, but can introduce artifacts.
• Understanding and mitigating these artifacts is crucial for reliable materials characterization.

Purpose of the Study:

• To investigate artifacts induced by Gallium (Ga) focused ion beam (FIB) polishing.
• To evaluate the suitability of using Neon (Ne) ions in a helium ion microscope (HIM) for sample preparation.
• To compare Ne-ion polishing with Ga-ion polishing for EBSD analysis.

Main Methods:

• Polishing copper samples using Ga and Ne ions with varying energies and incident angles.
• Utilizing EBSD to analyze the polished surfaces for microstructural integrity.
• Employing Monte Carlo simulations to understand ion-sample interactions and artifact formation.

Main Results:

• Ga FIB polishing induced crystal structure alterations and phase transformations (Cu to Cu3Ga).
• High-energy Ne ion polishing at a glancing angle preserved the crystal structure.
• Ne ion polishing significantly improved EBSD indexing accuracy compared to Ga ion polishing.

Conclusions:

• High-energy Ne ions at glancing incidence in a HIM are superior to Ga FIB for EBSD sample preparation.
• Reaching a steady-state condition of ion interaction depth quickly reduces specimen damage.
• Minimizing ion-induced artifacts is key to obtaining high-quality EBSD data.