Shot noise-mitigated secondary electron imaging with ion count-aided microscopy

Area of Science:

• Nanoscience
• Microscopy
• Materials Science

Background:

• Nanoscale imaging relies on detecting secondary electrons from charged particle beams.
• Measurement noise limits image quality and necessitates high particle doses, harming sensitive samples.
• Current methods improve image quality but don't address fundamental noise sources or provide quantitative scaling.

Purpose of the Study:

• Introduce a quantitative imaging technique, ion count-aided microscopy (ICAM).
• Mitigate noise sources and enable dose reduction in nanoscale imaging.
• Establish a physically meaningful scale for improved image interpretability.

Main Methods:

• Developed ICAM, a statistically principled method for estimating secondary electron yield.
• Implemented a change in data collection to reduce source shot noise.
• Applied ICAM to helium ion microscopy for dose reduction and performance validation.

Main Results:

• ICAM substantially reduces source shot noise.
• Demonstrated a 3× dose reduction in helium ion microscopy.
• Empirical results closely matched theoretical performance predictions.

Conclusions:

• ICAM provides a quantitative imaging solution for nanoscale applications.
• The technique facilitates imaging of dose-sensitive and fragile samples.
• ICAM may enhance the attractiveness of heavy particle microscopy.