Impact of Thin La2O3 Insertion for HfO2 MOSFET

As the scaling requires high-k material to replace the conventional SiO2 gate dielectric, HfO2 and its related oxides have been the major candidates to achieve equivalent oxide thickness (EOT) around 1 nm. Usually, thin layer of SiO2 or SiON is introduced as an interfacial layer (IL) in order to improve the relatively high interface state density or degraded effective carrier mobility (1). This IL will eventually increase the EOT and there exists a limitation in terms of further scaling. On this account, new process or additional material incorporation is strongly required. Recently, La2O3, one of the rare earth oxides, has attracted much attention as it has wide bandgap and high dielectric constant with fairly nice interface property (2). In this paper, the impact of thin layer La2O3 insertion under HfO2 layer on electrical properties of MOS capacitors and MOSFETs has been characterized.