PERFORMANCE OF THE PLASMA-DEPOSITED TUNGSTEN NITRIDE DIFFUSION BARRIER FOR AL AND AU METALLIZATION

The thermal stability of plasma-enhanced chemical-vapor-deposited tungsten nitride (PECVD-W-N) thin film has been investigated as a diffusion barrier between Al or Au and Si during subsequent annealing at 550-850-degrees-C. The atomic concentrations of N in as-deposited W100-xNx films are varied from 0 to 75 at.% corresponding to NH3/WF6 ratio, and their resistivities are varied f rom 10-460 muOMEGA . cm. Rutherford backscattering spectrometry, Auger electron depth profiles, X-ray diffraction and transmission electron microscopy show that 900 A PECVD-W67 N33 film interposed between Al or Au and Si is less permeable than sputtered TiN and PECVD-W film due to interstitial N atoms and Si/W67N33/Au maintaining the integrity of interface while the furnace post annealing is carried out at 850-degrees-C for 30 min.