High‐Temperature Active Oxidation and Active‐to‐Passive Transition of Chemically Vapor‐Deposited Silicon Nitride in N2–O2 and Ar–O2 Atmospheres

Abstract

The oxidation behavior of chemically vapor‐deposited silicon nitride in N2–O2 and Ar–O2 atmospheres was studied using a thermogravimetric technique at temperatures 1823 to 1923 K. Active oxidation was observed at low oxygen partial pressures. The active oxidation rates increased with increasing oxygen partial pressure (PO2) up to a certain PO2, and then passive oxidation occurred. The transition oxygen partial pressures from active to passive oxidation were determined. The rate‐controlling step for the active oxidation could be oxygen diffusion through a gaseous boundary layer near the Si3N4 surface. Decomposition of Si3N4 does not seem to be associated with the mass loss behavior. The Wagner model was employed to explain the oxidation behavior.