Nanoscale electron beam induced etching: a continuum model that correlates the etch profile to the experimental...

Area of Science:

• Materials Science
• Nanotechnology
• Surface Chemistry

Background:

• Electron beam induced etching (EBIE) is a key nanofabrication technique.
• Understanding the factors governing EBIE profiles is essential for precise nanoscale engineering.

Purpose of the Study:

• To develop a continuum model for electron beam induced etching.
• To investigate the influence of precursor adsorption, electron flux, and etch product desorption on nanoscale etching profiles.
• To elucidate the role of etch product diffusion, desorption, and re-dissociation.

Main Methods:

• Development of a series of continuum models with increasing complexity.
• Experimental validation using electron beam induced etching.
• Defocus experiment to probe different etching regimes.

Main Results:

• The model successfully relates experimental etching profiles to electron-limited and mass-transport-limited regimes.
• Precursor gas adsorption kinetics, electron flux distribution, and etch product desorption kinetics were shown to interact and affect the nanoscale etching profile.
• Etch product diffusion, desorption, and re-dissociation are critical factors influencing etching profiles, unlike in deposition models.
• Defocus experiments confirmed transitions between electron flux, mass transport, and etch product dissociation limited regimes.

Conclusions:

• A comprehensive continuum model is presented for electron beam induced etching.
• The study highlights the critical importance of etch product behavior (diffusion, desorption, re-dissociation) in understanding nanoscale etching.
• Experimental results validate the model and demonstrate the interplay of various limiting factors in EBIE.