Focused electron beam induced processing and the effect of substrate thickness revisited

Area of Science:

• Materials Science
• Nanotechnology
• Surface Science

Background:

• Focused electron beam induced processing (FEBIP) is a nanofabrication technique.
• Deposit growth in FEBIP is traditionally attributed to secondary electrons (SEs).
• The role of SEs from the support material in FEBIP growth kinetics requires further elucidation.

Purpose of the Study:

• To investigate the influence of support material properties on FEBIP growth rates.
• To determine the dominant electron type responsible for precursor dissociation in FEBIP on thin supports.
• To validate experimental findings with Monte Carlo simulations of SE emission.

Main Methods:

• Experimental FEBIP using amorphous carbon membranes of 1.4 nm and 4.3 nm thickness.
• Varying precursor pressures to observe effects on deposit growth.
• Monte Carlo simulations to model SE emission from the carbon supports.

Main Results:

• Early-stage FEBIP growth on thin membranes is support-dominated, with higher growth rates on thicker supports (4.3 nm vs 1.4 nm).
• Experimental results align with Monte Carlo simulations for SE emission, particularly for SEs with energies between 3-6 eV.
• At significantly reduced precursor pressures, the support thickness effect on growth rate diminished, suggesting a shift in growth dominance.

Conclusions:

• Secondary electrons play a crucial role in the initial stages of FEBIP on thin supports, influencing deposit growth rates.
• The growing deposit itself can become the dominant factor in precursor dissociation at later stages or under specific conditions (e.g., low precursor pressure).
• Understanding SE emission dynamics is critical for controlling FEBIP processes and optimizing nanostructure fabrication.