On the role of carrier gas in the deposition kinetics of SiO 2 films produced by low temperature chemical vapour deposition

Abstract

In this paper the results of experiments on the deposition rate as a function of the total gas flow rate and of the ratio of O 2 to SiH 4 under various experimental conditions and also the calculated plots of SiH 4 partial pressure and mixing time (the time available to the reactant gases to come in contact) vs. the total gas flow rate are presented. These data are interpreted in terms of the deposition mechanism and the homogeneous gas phase reaction as follows. (1) At low values of the total gas flow rate, where higher SiH 4 partial pressures and longer mixing times of reactant gases are obtained, a mass transport control (in terms of input gas flow rate limitation) is demonstrated. A homogeneous gas phase reaction is characteristics of this deposition region is determined by the SiH 4 partial pressure and/or mixing time. 1. (2) At medium values of the total gas flow rate the mass transport control ceases to determine the deposition kinetics, which considered to be diffus kinetically limited, while the intensity of the homogenous gas phase reaction is strongly decreased. 2. (3) At high values of the total gas flow rate where low input SiH 4 partial pressures and low mixing times of reactant gases are obtained it is shown rthat the surface kinetics control the deposition rate.