Low pressure chemicla vapor deposition from TEOS-NH_3 mixtures: thermochemiccal study of the process considering kinetic data

摘要

A caculational thermodynamic inestigation ofhte chemicla vapor deposition (CVD) of SiO_2 films from TEOS/NH_3 mixtures has been performed, by minimizing the Gibbs energy of the C-H-N-O-Si chemical system. Calculations are based on an upgraded thermodynamic data bank which includes silicon containing complex gaseous compounds. The obtained results illustrate the influence of temperature, of pressure, and of initial gas composition on the formation of stable phases. Partial equilibrium calculations were also performed, in order to investigate the predominant mechanisms for deposition. These calculations have been conduceted (a) by excluding hte solid phases from the calculations, and (b) by assuming a partial striping and elimination of the ethoxy ligands in the gas phase before reaching the growing surface. finally, the supersaturation of the gas phase relative to silicon the gas phase before reaching the growing surface. Finally, th esupersaturation of the gas phase reative to silicon dioxide and the corresponding driving force for th edeposition have been evaluated in different processing conditions. A direct relation between driving force and the growthn rate fothe deposits has thus been evidenced. The aim of this research is to contribute to the definition of optimum conditions for th eprocessing of materials whcih can be used as dielectrics in integrated circuits, and as waveguides in optoelectronics.