Influence of vacuum-annealing on the diffusion barrier properties of MOCVD TiN for Cu metallization

Abstract

We have investigated the effects of vacuum annealing of TDMAT-sourced TIN on the film qualities, as well as on the properties of the barrier against Cu diffusion. Vacuum annealing at 550 degrees C to 1000 degrees C achieved a significant densification of the TiN films with the interaction of Ti in the TiN prepared by metalorganic chemical-vapor deposition (MOCVD TiN) and Si at the interface. This interaction produced a stable interface between TIN and Si. In addition, annealing of the films at 1000 degrees C transformed the amorphous TiN(C) films into crystalline TiNC solid solutions. About 10 at% silicon diffused into the TIN film from the Si substrate, and oxygen in the as-deposited TIN film was expelled to the surface after annealing at 1000 degrees C. The barrier failure mechanism of MOCVD TiN in Cu metallization included the indiffusion of Cu and the accompanying outdiffusion of silicon through the barrier layer. The annealing of MOCVD TIN in vacuum improved the diffusion barrier properties, partly due to the densification of the MOCVD-TiN film and partly due to the formation of a stable interface.