Insights into ALD Growth of Al-Based Dielectric Stack on 4H-SiC

Galizia, Bruno and Schilirò, Emanuela and Fiorenza, Patrick and Giannazzo, Filippo and Pécz, Béla and Fogarassy, Zsolt and Roccaforte, Fabrizio and Lo Nigro, Raffaella (2026) Insights into ALD Growth of Al-Based Dielectric Stack on 4H-SiC. NANOMATERIALS, 16 (12). No. 782. ISSN 2079-4991

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Abstract

An Al2O3/AlN stack deposited via Atomic Layer Deposition (ALD) methods as a gate insulator for silicon carbide (4H-SiC) has been investigated, focusing on the effects of different Al2O3 deposition processes on the nitride layer. In particular, dielectric stacks, consisting of a 10 nm AlN interface (001)-oriented layer directly grown on a 4H–SiC substrate and in 20 nm of additional amorphous Al2O3 layers were synthesized in sequential deposition runs by thermal ALD (T-ALD) or plasma-enhanced ALD (PEALD) methods. The evolution of the phenomena occurring at the Al2O3/AlN interfaces has been established by in situ ellipsometry measurements. Strong effects of the oxygen plasma because of the O-Al-N bond formation have been clearly observed and corroborated by ex situ structural and electrical characterizations, especially in the case of the plasma-enhanced Al2O3 process. In particular, the Al2O3/AlN bilayer grown by the Al2O3 T-ALD method exhibited good insulating behavior and an 8.7-high dielectric constant was measured. By contrast, the Al2O3/AlN bilayer grown by the Al2O3 PEALD method demonstrated poor insulating properties.

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