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

Ultraviolet induced chemical vapor deposition was used to deposit sili con dioxide dielectrics on III-V materials at low temperature. Auger e lectron spectroscopy and nuclear reaction analysis measurements show t hat the nitrogen concentration in the layers decreases continuously wi th the total pressure. These results are in complete agreement with in frared 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 pre ssure. Bridging nitrogen (O3=Si-N-Si=O3) and oxygen-like-vacancy cente rs (E1') defects are observed in small quantities (almost-equal-to 10( 16) cm-3), while overcoordinated N defects are observed in concentrati ons up to 10(18) cm-3, depending upon deposition pressure. Such SiO2 f ilms were used in the processing of metal-insulator InP structures. Im provement of the electrical properties also occurs when the total pres sure is increased, in agreement with expectations founded on the elect ron spin resonance results.