PHASE-SEPARATION AND SODIUM PASSIVATION IN SILICON-OXIDES GROWN IN HCI-O2 AMBIENTS

The interrelationship which exists between sodium passivation and phase separation in silicon oxides thermally grown in HCl/O2 ambients was investigated using the capacitance-voltage bias temperature stress technique in conjunction with transmission electron microscopy. Oxides were grown in 0, 3, 6, and 10 volume percent (v/o) HCl for various times at 1100°, 1150°, and 1200°C. The threshold in passivation characteristic of these oxides was shown to be a steep portion of a continuous, smooth curve, rather than a sharp discontinuity. The microstructural investigation showed that the development of the additional, chlorine-rich phase correlates well with passivation. The development of this phase, characterized by growth and coalescence, is modeled in terms of phase transformation kinetics. © 1979, The Electrochemical Society, Inc. All rights reserved.