Termination-Dependent HF Activation on 4H-SiC (112-0): Pt-Ni-C-N₄ Dual-Atom Catalysts Promote Etching Kinetics─A...

Area of Science:

• Materials Science
• Surface Chemistry
• Computational Chemistry

Background:

• The ($11\stackrel{-}{2}0$) face of 4H-Silicon Carbide (SiC) is critical for semiconductor applications due to its high conductivity.
• Understanding its hydrofluoric acid (HF)-assisted wet etching mechanism is essential for optimizing semiconductor processing.
• Surface terminations and functional groups significantly influence the etching behavior.

Purpose of the Study:

• To investigate the HF etching mechanism on the ($11\stackrel{-}{2}0$) face of 4H-SiC.
• To elucidate the role of OH and coexisting F/OH surface terminations in the etching process.
• To identify strategies for efficient low-temperature etching.

Main Methods:

• First-principles calculations were employed to simulate the stepwise HF etching process.
• Analysis included reaction pathways, transition states, intermediates, and rate-determining steps.
• Investigated adsorption configurations, charge transfer, and bonding characteristics.

Main Results:

• HF dissociation is strongly dependent on surface termination, with lower activation energy on F-OH coterminated surfaces (2.51 eV) compared to OH-terminated surfaces (2.86 eV).
• Etching preferentially removes Silicon (Si) over Carbon (C), forming SiF₄, indicating complete fluorination selectivity.
• A Pt-Ni-C-N₄ dual-atom catalyst significantly reduces the energy barrier by ~1 eV, enabling ambient temperature etching.

Conclusions:

• Surface termination dictates the HF etching mechanism and energy barriers on the 4H-SiC ($11\stackrel{-}{2}0$) face.
• Complete fluorination of Si is favored during the etching process.
• The developed dual-atom catalyst offers a stable and cost-effective approach for low-temperature SiC etching.