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

Area of Science:

• Nanoscale imaging
• Quantitative microscopy
• Charged particle beam instrumentation

Background:

• Nanoscale imaging relies on detecting secondary electrons from charged particle beams.
• Image quality is limited by measurement noise and incident particle dose, especially for sensitive samples.
• Current methods do not fundamentally address noise sources or provide quantitative scaling.

Purpose of the Study:

• To introduce a quantitative imaging technique, ion count-aided microscopy (ICAM), for improved nanoscale imaging.
• To reduce source shot noise and enable accurate scaling of images.
• To facilitate imaging of dose-sensitive and fragile samples.

Main Methods:

• Developed ICAM, a technique using statistically principled estimation of secondary electron yield.
• Implemented a change in data collection during the imaging process.
• Applied ICAM to helium ion microscopy for experimental validation.

Main Results:

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

Conclusions:

• ICAM offers a quantitative approach to nanoscale imaging, overcoming limitations of existing methods.
• The technique enables imaging of dose-sensitive and fragile samples.
• ICAM may increase the attractiveness of using heavier particles for advanced imaging applications.