Quantitative secondary electron energy filtering in a scanning electron microscope and its applications

Area of Science:

• Materials Science
• Semiconductor Physics
• Analytical Chemistry

Background:

• Two-dimensional dopant mapping using SEM offers rapid, high-resolution analysis with minimal sample prep.
• Current SEM techniques lack reliable quantification, limiting widespread application.
• Quantitative energy filtering is needed to improve the accuracy of dopant concentration measurements.

Purpose of the Study:

• To develop and validate a quantitative energy-filtering method for SEM-based dopant mapping.
• To address the limitations of standard SEM imaging for accurate dopant analysis.
• To establish reliable quantification for secondary electron energy distributions.

Main Methods:

• Utilized a through-the-lens (TTL) detector in a field emission gun SEM (FEG-SEM).
• Quantified energy filtering by measuring the linear shift in secondary electron (SE) energy distribution with variable specimen bias.
• Employed copper wire samples and ray-tracing simulations for validation.

Main Results:

• Determined the experimental detector response (R(exp)) values ranging from 2.42±0.04 to 3.01±0.05.
• Validated results against ray-tracing simulations, establishing recommendations for the TTL detector's linear range.
• Successfully measured the potential difference across a Si pn-junction as 0.81±0.10 V.

Conclusions:

• Quantitative energy filtering with a TTL detector enables accurate 2D dopant mapping in FEG-SEM.
• The developed method overcomes previous quantification challenges in SEM dopant analysis.
• This technique provides a reliable approach for characterizing semiconductor materials.