Scaling analysis of, chemical-vapor-deposited tungsten films by atomic force microscopy

We have studied the static surface roughness of 500-nm thick tungsten chemical-vapor-deposited polycrystalline films on length scales between 5 and 5 × 10⁴ nm, using atomic force microscopy. The interface width scales as a power of the system size for small system sizes (<1000 nm) but is constant for large sizes, which is in agreement with nonequilibrium interface growth theory. The scaling exponent (0.75 ± 0.05) for short-length scales appears to be consistent with the recent prediction based on a conservative volume growth model. In the long-range regime, the rms value becomes larger as the substrate temperature is lowered.