Effects of deposition conditions on step-coverage quality in low-pressure chemical vapor deposition of HfO2

Hafnium dioxide thin film is deposited on a Si substrate with trenches by LPCVD using the Hf(NEt2)(4)/O-2 gas system. When the deposition temperature is 300degreesC, poor-quality step-coverage is obtained. The step-coverage quality improves as the deposition temperature increases, and the good-quality step coverage is achieved at 450degreesC. By analyzing the profile of the film thickness in the trench, it is suggested that there are at least two types of important reactants that contribute to the film deposition. One is an active reactant. The contribution of this adsorbate to the film deposition decreases as the substrate temperature increases. On the other hand, the other reactant is a slightly active reactant. When a film is deposited at 450degreesC, most of the film is deposited from this slightly active adsorbate and good-quality step coverage is obtained. (C) 2002 Elsevier Science B.V. All rights reserved.