A Dual-Si Atomic Precursor Enabling High-Quality SiN x Thin Films via Very High-Frequency Plasma Atomic Layer Deposition

Abstract Silicon nitride (SiNx), an effective barrier layer in advanced electronic devices thanks to its exceptional resistance to both chemical and environmental degradation, is typically deposited via plasma-enhanced atomic layer deposition (PE-ALD). Among various plasma configurations, very high-frequency (VHF) plasma sources have attracted significant interest for the deposition of SiNx because of their potential to enhance film density and conformality, as well as to minimize substrate damage. Additionally, since the precursor properties play an important role in determining the growth behavior and quality of thin films, exploring various precursors is essential for optimizing SiNx deposition. Therefore, in this study, we introduce [SiHN(CH3)2CH3]2NH (bis(dimethylaminomethylsilyl)amine; NSi-01) as a dual-Si atomic precursor for VHF PE-ALD and compare it with two conventional counterparts─[(CH3)3CNH]2SiH2 (bis(tert-butylamino)silane; BTBAS) and SiH2[N(CH2CH3)2]2 (bis(diethylamino)silane; BDEAS). A comprehensive analysis of the dual-Si atomic structure and adsorption mechanism of NSi-01 reveals that only one methyl ligand actively participates in surface reactions. This distinctive adsorption behavior yields SiNx with a lower dielectric constant and better electrical characteristics compared to those obtained from BTBAS and BDEAS. These results provide a key understanding of the precursor selection that influences the properties and quality of thin films deposited via VHF PE-ALD.