INFLUENCE OF PRESSURE ON NITROGEN INCORPORATION IN ULTRAVIOLET CHEMICAL-VAPOR-DEPOSITED SIO2-FILMS

Ultraviolet induced chemical vapor deposition was used to deposit silicon dioxide dielectrics on III-V materials at low temperature. Auger electron spectroscopy and nuclear reaction analysis measurements show that the nitrogen concentration in the layers decreases continuously with the total pressure. These results are in complete agreement with infrared transmission spectroscopic and ellipsometric measurements. The number and the nature of the paramagnetic defects measured by electron spin resonance are also shown to be dependent upon the deposition pressure. Bridging nitrogen (O3=Si-N-Si=O3) and oxygen-like-vacancy centers (E1') defects are observed in small quantities (almost-equal-to 10(16) cm-3), while overcoordinated N defects are observed in concentrations up to 10(18) cm-3, depending upon deposition pressure. Such SiO2 films were used in the processing of metal-insulator InP structures. Improvement of the electrical properties also occurs when the total pressure is increased, in agreement with expectations founded on the electron spin resonance results.