Characterization in Silicon Processing

the metal defects and minimizes interface state densities in MOS devices. Thus,

refractory metals are suitable for barrier application because of their high melting

point,

high activation energy for grain boundary diffusion, and low self-diffusion

coefficient at

room

temperature. However, refractory metal films exhibit a fine-

grained

microstructure because of the low mobility of atoms at deposition and

processing temperatures, resulting in a large grain boundary area. The activation

energy

for grain boundary diffusion is lower

than

that

for lattice diffusion, and the

grain

boundary areas are active paths for interdiffusion across the barrier ...