Effect of trimethyl aluminium surface pretreatment on atomic layer deposition Al2O3 ultra-thin film on Si substrate

Ultra-thin Al2O3 dielectric films have been deposited on Si substrates by using trimethyl aluminium (TMA) and water as precursors in an atomic layer deposition (ALD) system. Growth of the interfacial layer between ultra-thin Al2O3 and the Si substrate is effectively suppressed by a long-time TMA surface pretreatment of the Si substrate prior to Al2O3 atomic layer deposition. High resolution transmission electron microscopy (TEM) images show that the thickness of the interfacial layer is reduced to be 0.5 nm for the sample with TMA pretreatment lasting 3600 s. The x-ray photoelectron spectroscopy results indicate that the Al2O3 Elm deposited on the TMA-pretreated Si surface exhibits very good thermal stability. However, a hysteresis of about 50 mV is observed in the C-V curve of the samples with the TMA pretreatment.