Journal of Applied Physics vol:100 issue:11 pages:114903-1-114903-6
Atomic layer deposition (ALD) of tungsten nitride carbide (WNxCy) on methyl-terminated self-assembled monolayers (SAMs) is investigated. SAM substrates provide extended transient regimes of different lengths, during which the WNxCy film growth is nonlinear. The extent of this offset from linear growth depends on the alkyl chain length. The film morphology is characterized by atomic force microscopy, which reveals island growth and fractal behavior. During the transient regime, WNxCy deposition shows nonconservative growth, as revealed by the low film density and a roughness exponent alpha of similar to 0.4-0.5. During the linear growth regime, a conservative mechanism is observed, characterized by a higher, constant film density and alpha similar to 0.7. These observations do not apply to all ALD deposited films. In particular, ALD HfO2 films follow a conservative-type mechanism during the entire range of growth. (c) 2006 American Institute of Physics.