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Updated: Jun 9, 2026
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Published on: June 23, 2023
Gas cascade amplification in ultra-high-resolution environmental scanning electron microcopy
Milos Toth1, Bradley L Thiel, W Ralph Knowles
1FEI Company, 5350 NE Dawson Creek Drive, Hillsboro, OR 97124, USA. milos.toth@FEI.com
Summary
A feedback mechanism in environmental scanning electron microscopy (ESEM) gas amplification significantly impacts imaging signal and noise. This finding aids in optimizing ESEM for advanced metrology and nanostructure imaging.
Area of Science:
- Physics
- Materials Science
- Microscopy
Background:
- Environmental scanning electron microscopy (ESEM) utilizes gas cascade amplification for imaging.
- Understanding gas gain mechanisms is crucial for optimizing ESEM performance.
Purpose of the Study:
- To describe a feedback mechanism in the ESEM gas cascade amplification process.
- To investigate its effect on imaging signal and noise under ultra-high-resolution conditions.
Main Methods:
- Analysis of the gas cascade amplification process in magnetic immersion lens ESEM.
- Observation of signal and noise dependencies on microscope operating parameters.
Main Results:
- A feedback mechanism dominates gas gain in ultra-high-resolution ESEM.
- Novel dependencies of imaging signal and noise on operating parameters were identified.
- Feedback is tentatively attributed to free electron generation from metastable species de-excitation.
Conclusions:
- The identified feedback mechanism is critical for understanding ESEM performance.
- Results provide insights for optimizing ESEM systems for critical dimension metrology.
- Implications for real-time imaging of nanostructure growth via gas-mediated electron beam induced deposition.
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