Interfacial reactions in the Si/TaC/Cu system

摘要

Interfacial reactions in the Si/TaC/Cu metallization system were investigated by utilizing transmission electron microscopy and a combined kinetic and thermodynamic analysis. The formation of an amorphous Ta[C,O] layer was observed at the TaC/Cu interface at 600℃. After annealing at the same temperature a thin amorphous layer was detected also at the Si/TaC interface. After annealing at 750℃ the thickness of the amorphous layer .at the Si/TaC interface had increased and a mixture of crystalline and amorphous phases could be detected inside the TaC layer. This was anticipated to be the preliminary stage of the formation of SiC and TaSi_2 that occurred at 800℃. Overlapping with thickening of the amorphous layer formation of large Cu_3Si precipitates took place and the layered metallization structure was partially destroyed. In order to obtain more information on the reactions at the Si/TaC interface and the effect of oxygen on the stability of TaC the ternary Si-Ta-C and Ta-C-O phase diagrams were evaluated from the assessed binary data. Activity diagram was also calculated to evaluate the possible reaction sequence at the Si/TaC interface. The observed reaction structure was found to be consistent with the thermodynamics of the ternary system.