Effect of growth temperature on AlN thin films fabricated by atomic layer deposition

Abstract

Resistive random-access memories (RRAM) have been extensively studied because of their advantages such as low operating voltage, high reliability, and simple structure. Among the various types of materials for RRAMs, such as oxides, nitrides, sulfides, and chalcogenides, AlN shows resistive switching phenomena with low energy and high speed via the formation of Al-rich conducting channels owing to the generation of nitrogen vacancies. Moreover, AlN has a large band gap (~ 6.2 eV), high thermal conductivity, and dielectric constant. Therefore, AlN can find application as a gate dielectric material, functional layer, and resistive switching layer for RRAM applications. In this study, AlN thin film is deposited by thermal atomic layer deposition (ALD), which is a self-limiting technique through ligand exchange between the precursor molecules and surface functional groups. We use trimethylaluminum (TMA) and NH3 as the metal precursor and reaction gas, respectively. We obtain growth rates of 0.05–0.16 nm/cycle at a wafer temperature of 274–335 °C. Structural and chemical properties of the AlN films grown at various temperatures are investigated by X-ray diffraction, Auger electron spectroscopy, and X-ray photoelectron spectroscopy. The electrical properties of these AlN films are studied by fabricating the devices having an Al/AlN/Pt stack.