High-resolution transmission electron microscopy and electron energy-loss spectroscopy study of polycrystalline-Si/ZrO2/SiO2/Si metal-oxide-semiconductor structures

Abstract

Crystallographic and interfacial characteristics of polycrystalline-Si/ZrO 2 / SiO 2 /Si metal-oxide-semiconductor (MOS) structures were investigated at the atomic scale by high-resolution transmission electron microscopy (HRTEM) and electron energy-loss spectroscopy (EELS) combined with the annular dark-field scanning transmission electron microscopy. The HRTEM and electron diffraction results showed that the ZrO 2 film exhibited a mixed structure of the tetragonal (P4m2) and the monoclinic (P2 1 /c) phases. Moreover, Zr-Si nodules formed by the reaction of Zr with polycrystalline-Si were evaluated to be ZrSi 2 of the orthorhombic phase or Zr 5 Si 4 of the tetragonal phase. From the EELS results, Zr atoms were detected at the upper and bottom interfaces of the SiO 2 film, and the interfacial SiO 2 layer with thickness <1 nm was observed at the polycrystalline-Si/ZrO 2 interface. The interfacial reactions directly influence the electrical properties of the MOS structures.