|
At present the primary material for the metalization of the
ULSI(ultra-large scale integration) is aluminum. The goal of
achieving high reliability and yield for ULSI fabrication can
only be realized with the advanced annealing technology. We
applied two different annealing processes on our multi-layer
system in which Al films were sputtering deposited and TiN
films were deposited with the reactive sputtering. The effects
of the annealing process on the TiN diffusion barrier, surface
morphology, and interdiffusion and reactions between
interfaces, was executed by x-ray diffraction (XRD), scanning
electron microscopy（SEM）, optical microscopy, Auger electron
spectroscopy and Rurtherford backscattering spectroscopy.
Experimental results revealed that aluminum melted locally at
the unstable area and forming holes on the surface of samples.
AlN and Al3Ti formed at the interface between Al and TiN. The
formation of titaniumsilicide between Ti and Si was also
obsvered. It is believed that atoms will diffuse through the
barrier film via defects in the barrier films, such as grain
boundaries or voids. Furnace annealing makes those defects
combine into voids and the Al atoms can be more easily to
diffuse through the barrier during annealing at the temperature
of 550℃. On the other hand, in-situ annealing produced fewer
defects associated with the TiN barrier film and therefore
could avoid the surface reactions and interdiffusion with Al
and enhanced the barrier quality.
|