Deposition kinetics of silicon dioxide from hexamethyldisilazane and oxygen by PECVD

Silicon oxide films were deposited on silicon wafers of 200 degrees C in a radio frequency reactor from gas mixtures of hexamethyldisilazane and oxygen at various discharge powers and oxygen flow rates. Kinetics of the deposition of silicon dioxide was studied by using a simple surface chemistry model combined with the electron induced dissociation model developed in our previous work. The validity of the combined model was examined by investigating the behavior of the incorporation rate of Si-O-Si bonds into the films in terms of the discharge power. According to the model, in the regime of the negligible contribution of ion bombardment the incorporation rate psi, is expressed as psi(infinity)/psi = 1 + chi(-1) P-rf(-1), with psi(infinity) = psi at the discharge power, P-rf = infinity.chi is a parameter independent of P-rf and designates the efficiency of dissociation of oxygen molecules per inputted power under the experimental conditions of this work. The experimental results showed that the incorporation rate for the films deposited at oxygen flow rates of 10, 30 and 50 sccm and at a monomer flow rate of 3 g/h followed the prediction of the model very well. The values of chi were estimated to be in the order of similar to 1.0 x 10(-2)W(-1) and decreased as the oxygen flow rate increased. The decrease in chi was explained by using the uniform discharge model for an electronegative discharge. (C) 1999 Elsevier Science S.A. All rights reserved.