Tuning surface reactivity pathways through molecular inhibitor redosing for precision nanopatterning.

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Area-selective atomic layer deposition (AS-ALD) is vital for precise 3D nanofabrication.
• Achieving high selectivity in AS-ALD remains a challenge for complex structures.

Purpose of the Study:

• To investigate ruthenium (Ru) AS-ALD on SiO2 versus Si3N4 surfaces.
• To enhance AS-ALD selectivity using a small molecule inhibitor (SMI) and a re-dosing strategy.
• To evaluate the impact of surface topography on AS-ALD performance in 2D and 3D patterns.

Main Methods:

• Utilized cyclohexane carboxaldehyde (CHAD) as a small molecule inhibitor (SMI) for selective adsorption on Si3N4.
• Employed tricarbonyl-(trimethylenemethane)-ruthenium (TRuST) precursor and H2O reactant for Ru deposition.
• Implemented a re-dosing strategy for CHAD, validated by Monte Carlo (MC) simulations, to improve selectivity.
• Applied optimized Ru AS-ALD to 2D line and 3D trench patterns composed of SiO2/Si3N4.

Main Results:

• CHAD demonstrated selective adsorption on Si3N4, enabling selective Ru deposition.
• The re-dosing strategy significantly improved Ru AS-ALD selectivity up to 27 nm (200 cycles) compared to a single dose (7 nm, 50 cycles).
• 3D trench patterns achieved 15 nm selective growth (100 cycles) without lateral growth, outperforming 2D patterns (26.5 nm selective deposition with 18.8 nm lateral growth).

Conclusions:

• The re-dosing strategy effectively enhances selectivity in AS-ALD by increasing inhibitor adsorption density.
• Surface topography plays a critical role, with 3D trench structures offering superior physical and chemical barriers for reliable AS-ALD.
• The study demonstrates a promising approach for achieving high-selectivity AS-ALD in 3D nanofabrication.