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Combining focused ion beam and atomic layer deposition in nanostructure fabrication
Zhongmei Han1, Marko Vehkamäki, Markku Leskelä
1Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki, FIN-00014, Finland.
Nanotechnology
|February 22, 2014
Summary
Focused ion beam milling combined with atomic layer deposition enables 3D nanostructure fabrication. Optimizing ion beam angles enhances thermal stability of milled silicon, crucial for microelectronic device prototyping.
Area of Science:
- Materials Science
- Nanotechnology
- Surface Science
Background:
- Combining atomic layer deposition (ALD) and focused ion beam (FIB) milling offers advanced 3D nanostructure fabrication.
- ALD is crucial for thin films in microelectronics and MEMS, but thermal stability of FIB-milled silicon is a challenge due to segregation and roughening at typical ALD temperatures (200-500°C).
Purpose of the Study:
- To investigate the thermal stability of gallium FIB-milled silicon structures after annealing.
- To determine the optimal FIB milling parameters for improved thermal stability.
- To assess the feasibility of ALD Al2O3 growth on FIB-milled silicon surfaces.
Main Methods:
- Silicon substrates were milled using a gallium FIB at various incident angles.
- Milled samples were annealed at 250°C.
- The amount of implanted gallium was quantified.
- Atomic layer deposition of Al2O3 was performed on the milled and annealed silicon.
Main Results:
- Gallium implantation decreased significantly with increasing ion beam incident angle relative to the surface normal.
- A 60° incident angle provided a balance between thermal stability and milling efficiency.
- ALD Al2O3 deposition at 250°C was successful on all milled silicon surfaces, even those exhibiting segregation.
- ALD Al2O3 served to create uniform surfaces and narrow milled trenches.
Conclusions:
- Increasing FIB incident angle enhances the thermal stability of milled silicon nanostructures.
- ALD Al2O3 can be effectively used to stabilize and refine FIB-milled silicon features for microfabrication.
