Effects of N2 remote plasma nitridation on the structural and electrical characteristics of the HfO2 gate dielectrics grown using remote plasma atomic layer deposition methods

Abstract

The characteristics of remote plasma atomic layer deposited HfO2 on Si, which has a very thin SiO2 interlayer with and without remote plasma nitridation (RPN), have been investigated. Small amounts of N atoms were successfully incorporated by RPN pretreatment, in which the dominant emission species were excited atomic nitrogen (N*) and excited molecular nitrogen (N2*), into a very thin SiO2 interlayer for the growth of HfO2 thin film. The thin (∼1.5nm) intermediate layer containing nitrogen, which was prepared by sequential O2 and N2 remote plasma treatment of the Si substrate, can effectively suppress growth of the unintentional interface layer. In addition, it enhances the thermal stability and the resistance to oxygen diffusion during rapid thermal annealing. The HfO2 film containing the remote plasma nitrided SiO2 interlayer annealed at 800°C showed a lower equivalent oxide thickness of ∼1.89nm and a lower leakage current density (3.78×10−7Acm−2 at ∣VG−VFB∣=2V) compared to a non-nitrided sample of the same physical thickness. Also, we compared the characteristics of HfO2 films annealed in two different ambient environments, N2 and O2.