Open AccessDynamics of nucleation in chemical vapor deposition
Author(s) -
Thomas Mayer,
David P. Adams,
B. S. Swartzentruber,
Eric Chason
Publication year - 1995
Language(s) - English
Resource type - Reports
DOI - 10.2172/170570
Subject(s) - nucleation , autocatalysis , chemical vapor deposition , dissociation (chemistry) , scanning tunneling microscope , chemical physics , desorption , kinetics , island growth , hydrogen , materials science , nanostructure , metal , chemical engineering , chemistry , nanotechnology , layer (electronics) , adsorption , epitaxy , metallurgy , physics , organic chemistry , quantum mechanics , engineering
We study the evolution of layer morphology during the early stages of metal chemical vapor deposition (CVD) onto Si(100) via pyrolysis of Fe(CO){sub 5} below 250{degrees}C. Scanning tunneling microscopy (STM) shows that nuclei formation is limited by precursor dissociation which occurs on terraces, not at step sites. Also, the average size of clusters formed during CVD is larger than for Fe growth by evaporation (a random deposition process). Based on STM data and Monte Carlo simulations, we conclude that the CVD-growth morphology is affected by preferential dissociation of Fe(CO){sub 5} molecules at existing Fe clusters -- an autocatalytic effect. We demonstrate that nucleation kinetics can be used to control formation of metal nanostructures on chemically tailored surfaces. Reactive sites on Si (001) are first passivated by hydrogen. H atoms are locally removed by electron stimulated desorption using electrons emitted from the STM tip. Subsequent pyrolysis of Fe(CO){sub 5} leads to selective nucleation and growth of Fe films in the areas where H has been removed