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 0.5nm for the sample with TMA pretreatment lasting 3600s. The x-ray photoelectron spectroscopy results indicate that the Al₂O₃ film deposited on the TMA-pretreated Si surface exhibits very good thermal stability. However, a hysteresis of about 50mV is observed in the C--V curve of the samples with the TMA pretreatment.