Ferroelectric property of an epitaxial PZT/Ir/ZrN/Si structure by sputtering

Heteroepitaxial (100)ZrN, (100)Ir and (001)PZT films were deposited on a (100)Si substrate in sequence by sputtering. The 300-nm-thick epitaxial PZT film with the top electrode of IrO₂ showed relatively good electrical properties. Although no interdiffusion between PZT and Si through the Ir/ZrN layer was observed from XPS analysis, it was found that the ZrN film was oxidized during Ir film deposition. This oxidation can be suppressed somewhat by increasing the deposition rate and decreasing the substrate temperature. However, in order to suppress oxidation completely, we propose a new sputtering target in which small Zr metallic plates are placed in a circular fashion on the non-erosion area of the Ir target. Using this target, oxidation of the ZrN film was not observed and the contact resistivity of the Ir/ZrN layer to the Si substrate was reduced to 490 μΩcm²