Mechanistic Atomic Hydrogen Chemistry for Ruthenium Deposition: From Ligand Elimination to Area-Selective Patterning

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Atomic layer deposition (ALD) of ruthenium (Ru) is crucial for semiconductor applications.
• Conventional Ru ALD faces challenges like interfacial oxide formation and oxygen diffusion due to combustion reactions.
• Existing reduction-based ALD using H2 requires high temperatures to overcome dissociation energy barriers.

Purpose of the Study:

• To develop a low-temperature ALD process for high-purity ruthenium films.
• To circumvent the high energy barrier associated with H2 dissociation in Ru ALD.
• To enable area-selective deposition of Ru films with improved selectivity.

Main Methods:

• Utilized dissociated atomic hydrogen as a reactant to lower the energy barrier for precursor ligand removal.
• Investigated the interaction between atomic hydrogen and inhibitor molecules for area-selective deposition.
• Employed theoretical analyses including density functional theory, molecular dynamics, and Monte Carlo simulations to understand reaction pathways.

Main Results:

• Achieved growth of high-purity metallic Ru films with low resistivity (23.7 μΩ·cm) at a reduced temperature of 100 °C.
• Successfully demonstrated area-selective deposition by addressing inhibitor layer partial removal with a redosing strategy.
• Elucidated the reactivity and reaction mechanisms of dissociated species through comprehensive theoretical modeling.

Conclusions:

• Atomic hydrogen enables a lower-temperature, high-purity Ru ALD process, overcoming limitations of conventional methods.
• The developed ALD process is suitable for area-selective deposition, with strategies to enhance selectivity.
• Theoretical analyses provide fundamental insights into the reaction dynamics of dissociated species in Ru ALD.