Study of curtaining effect reduction methods in Inconel 718 using a plasma focused ion beam

Area of Science:

• Materials Science
• Surface Engineering
• Nanotechnology

Background:

• The curtaining effect is a significant challenge in focused ion beam (FIB) surface preparation, particularly for materials like Inconel 718.
• This phenomenon degrades the quality and accuracy of prepared cross-sections, impacting subsequent analyses.

Purpose of the Study:

• To investigate and evaluate methods for mitigating the curtaining effect during plasma FIB milling of Inconel 718.
• To assess the impact of different protective strategies on cross-section quality under varying ion beam conditions.

Main Methods:

• Exploration of Platinum (Pt) deposition, silicon (Si) mask, and Xenon difluoride (XeF2) gas injection as protective measures.
• Evaluation under high (30 kV-1 µA) and medium (30 kV-100 nA) ion beam current conditions.
• Quantitative assessment of curtaining reduction and cross-section quality using Atomic Force Microscopy (AFM) topography.

Main Results:

• XeF2 gas injection significantly improved cross-section quality at medium ion beam currents.
• Pt deposition and Si masks individually reduced curtaining, showing greater effectiveness at 100 nA.
• The Si mask was more effective than Pt deposition in reducing cross-section curvature.
• Combining protective layers (Pt/Si) with XeF2 injection led to layer degradation and reappearance of curtaining.

Conclusions:

• XeF2 gas is a promising method for improving cross-section quality in FIB milling of Inconel 718 at medium ion currents.
• Pt deposition and Si masks are effective for mitigating curtaining, especially at lower ion currents.
• Synergistic application of protective layers and gas assistance requires careful optimization to avoid detrimental effects.