Characteristics of Metal–Oxide–Semiconductor Field-Effect Transistors with HfO2/SiO2/Si and HfO2/SiOxNy/Si Stack Structures Formed by Remote Plasma Technique

Abstract

Thin SiO2 and SiOxNy layers were grown on Si substrates using remote plasma oxidation and nitridation, respectively, to use as buffer layers prior to HfO2 deposition. Subsequently, HfO2 films were grown on these buffer layers by remote plasma atomic layer deposition (RPALD). The SiO2 and SiOxNy buffer layers suppressed the growth of Hf silicate at the interface during HfO2 deposition, suppressed the increase in total oxide capacitance, and induced the decrease in effective fixed oxide charge density. Metal–oxide–semiconductor field-effect transistors (MOSFETs) with buffer layers exhibited a higher drain current (Id) and effective carrier mobility (µeff) than those without buffer layers. The incorporated N atoms in SiO2 buffer layer reduced both Id and µeff of MOSFETs due to the increase of defect charge in the interfacial region, compared to SiO2 buffer layer including no N atom.