Effects of CVD oxide on phosphorus-diffused emitters in silicon

Contact windows on phosphorus-diffused emitters have been made in layers of SiO2obtained by either thermal growth or CVD. Transistors with CVD oxide show a current gain which is 20 to 50 percent higher than that of transistors made with thermal oxide. TEM studies revealed stacking faults in the emitter region of transistors with CVD oxide, but dislocations for those with thermal oxide. We attribute the difference in current gain to the different crystallographic defect types in the neutral region of the emitter.