A Route to MoO2 film fabrication via atomic layer deposition using Mo(IV) precursor and oxygen reactant for DRAM applications

Abstract

Among the various molybdenum oxide (MoOx) films, molybdenum dioxide (MoO2) has gained significant attention as a promising electrode material for metal-insulator capacitors owing to its exceptional crystalline properties and high work function (WF). However, achieving precise atomic layer deposition of MoO2 films requires careful selection of molybdenum (Mo) precursors and oxidants, given the metastable nature of MoO2. Furthermore, film properties can vary depending on the oxidation potential of the reactant. In this study, we successfully deposited MoO2 films by utilizing Mo (NMe2)4 as the Mo source, which reacted with an O source (oxygen gas or ozone). MoOx(O2) and MoOx(O3) films exhibited significantly different growth rates, measuring approximately 0.23 and 1.36 Å/cycle, respectively. Additionally, MoOx(O2) and MoOx(O3) exhibited high WFs of 4.81 and 5.12 eV, respectively. Finally, hydrogen (H2) annealing induced a monoclinic phase in MoO2. By contrast, MoOx(O3) exhibited an orthorhombic structure after both H2 and O2 annealing, suggesting that the crystal structure was independent of the annealing atmosphere. These findings highlight the possibility that when a MoO2 layer that is well crystallized through H2 treatment is applied as an electrode for dynamic random-access memory(DRAM) capacitors, high-k crystal-inducing effects can be functionalized, and the leakage current can be reduced through the Schottky emission barrier.