Influence of oxidant source on the property of atomic layer deposited Al2O3 on hydrogen-terminated Si substrate

• DOI: 10.1016/j.tsf.2004.09.035
• Publication Date: 2005-02-09T04:14:44Z
• Authors: Seung-Chul Ha; Eunsuk Choi; Soo-Hyun Kim; Jae Sung Roh
• Keywords: Suboxide

Abstract Al 2 O 3 thin films were deposited on hydrogen-terminated Si substrate using atomic layer deposition (ALD) technique with tri-methylaluminum (TMA) and an oxidant source of H 2 O vapor, O 2 plasma, or O 3 . Substrate temperature was maintained at 350 °C when the Al 2 O 3 films were grown with the oxidant sources of H 2 O vapor and O 3 , and with the oxidant source of O 2 plasma, Al 2 O 3 films were deposited at the substrate temperature of 200 °C. Growth rates of Al 2 O 3 films on HF-cleaned Si surface were saturated at 0.08, 0.14, and 0.06 nm/cycle for H 2 O vapor, O 2 plasma, and O 3 , respectively. Equivalent oxide thickness (EOT) and leakage current vs. physical thickness of atomic layer deposited Al 2 O 3 films grown with various oxidant sources were also measured in this study. To investigate the main cause of different EOT with oxidant sources, interfacial properties were examined by using transmission electron microscopy (TEM) and X-ray photoelectron microscopy (XPS). In the TEM analysis, interfacial layers with the thickness of about 1.7 and 1.3 nm were observed in as-deposited Al 2 O 3 films grown using O 2 plasma and O 3 . We confirmed that the interfacial layers were mainly composed of SiO x in the XPS depth analysis. Using angle resolved X-ray photoelectron spectroscopy, effect of annealing on the interfacial structure of Al 2 O 3 films grown with O 3 and O 2 plasma was also studied, and we found that after annealing, the peak corresponding to silicon suboxide and Al-silicate disappeared and fully oxidized Si 4+ increased.