Study of Interfacial Interaction between Nitride Ceramics using Molecular Dynamics Simulations and Ab Initio Calculations

Abstract

With an increase in importance of power devices, nitride ceramics which exhibit a high heat conductivity have been paid an attention as materials of insulating substrates. As for an active metal brazing of a silicon nitride (Si₃N₄) ceramic substrate, a titanium nitride (TiN) reaction layer has been observed on the Si₃N₄ surface. In this study, both of molecular dynamics simulations and ab initio calculations were performed to elucidate the dependence of strength and stability of TiN/Si₃N₄ interface on crystal planes of TiN. The results indicated that the TiN(111)/Si₃N₄(11-20) interface was comparatively stable and strong. Interfacial bonding analyses revealed that there was a covalent bond between a Ti atom and a Si atom, which suggested to relate to the interfacial stability. Moreover, the lower lattice mismatch of TiN(111)/Si₃N₄(11-20) interface was comparable to that of TiN(112)/Si₃N₄(11-20) interface. Therefore, not only the lattice mismatch but also the interfacial chemical bonding suggested to affect strength and stability of TiN/Si₃N₄ interface.