Nanoscale focused electron beam induced etching of nickel using a liquid reactant

Area of Science:

• Materials Science
• Nanotechnology
• Surface Science

Background:

• Nickel nanostructures are vital for magnetic systems, lithography, and EUV mask absorbers.
• Electron-beam induced etching of nickel is needed for high-resolution mask repair, but lacks suitable gas-phase reactants.
• Existing methods face challenges in achieving precise nickel patterning without substrate damage.

Purpose of the Study:

• To investigate electron-beam induced local etching of nickel using a liquid reactant.
• To explore the feasibility of using aqueous sulfuric acid for nickel nanostructure patterning.
• To optimize etching parameters for high-resolution nickel modification.

Main Methods:

• Focused electron beam irradiation in an environmental scanning electron microscope (ESEM).
• Utilized aqueous sulfuric acid as a liquid reactant for nickel etching.
• Investigated parameters including electron dose, refresh time, and surfactant addition.

Main Results:

• Successful local etching of nickel was achieved using electron-beam irradiation in aqueous sulfuric acid.
• Etching occurred only in the electron-beam exposed areas, with no spontaneous etching.
• Etch extent increased with dose, while resolution improved with surfactant addition, enabling sub-micron features.
• Complete nickel film removal was achieved without damaging underlying layers.

Conclusions:

• Electron-beam induced etching with liquid sulfuric acid offers a viable method for high-resolution nickel patterning.
• This technique shows promise for repairing and editing nickel-based masks and templates in EUV lithography.
• Further refinement could overcome significant obstacles in nickel's application in advanced lithographic processes.