Abstract
Aluminum films with smooth surface morphology have been deposited selectively on silicon substrates by use of the double wall chemical vapor deposition system, in which the substrate is positioned between two heaters with different temperatures. The surface of Al films is smooth when the temperature of the heater facing the deposition side of the substrate is higher than that of the other heater, and selective deposition occurs at comparatively low substrate temperatures. The mechanism by which the smooth film forms is discussed using classical nucleation theory. When the source gas is heated to a high temperature at the front heater and is activated or partially decomposed, the supersaturation ratio increases twofold and the areal density of nuclei increases tenfold. Smooth films are then formed by the coalescence of these small nuclei. Selective Al growth is also shown to be related to the nucleation process in the initial stage of film growth. The activation energy of nucleation on an insulator substrate is estimated to be prohibitively high. © 1999 The Electrochemical Society. All rights reserved.
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