Constitution of Nitrided Oxides and Reoxidized Nitrided Oxides on Silicon

摘要

Nitriding thermal oxide on silicon-i.e., exposing an oxidized silicon wafer to ammonia at high temperature-has been shown to cause significant changes in the composition was well as in important physical properties of the oxide film. This laboratory has conducted studies of the changes in composition, electrical properties, and radiation resistance consequent o nitridation, and has examined reoxidation as a means of modifying such changes. Chemical analysis has been made of 361-A thermal oxide films nitrided in ammonia and also subsequently reoxidized in oxygen at 1000 C, using techniques of ellipsometry and infrared spectrometry. The nitrided film is shown to have a three-layer structure consisting of 22 A of 48% nitrogen, 334 A of 17% nitrogen, and 7.4 A of 100% nitrogen, where the fractions refer to % N/(N+0). After oxidation, the interface layer was unchanged and the surface merged into the bulk, the nitrogen content of which was reduced to 11%. The void content has also been determined.