Hydrogen Reintroduction by Forming Gas Annealing to LPCVD Silicon Nitride Coated Structures

Abstract

The effect of high-temperature anneals on low-pressure chemical-vapor deposited (LPCVD) /thermally grown stacks on silicon wafers has been studied. Annealing in a nitrogen atmosphere at 900 or for causes a substantial reduction in both and bond concentration in the nitride film and a significant degradation of surface passivation. Subsequent anneals in forming gas (95% Ar/5% ) at temperatures in the range lead to a gradual reformation of and bonds and an improvement in surface passivation. It is hypothesized that the chief mechanism responsible for the improvement in surface passivation is the passivation of defects at the interface with atomic hydrogen, supplied by the breaking of and bonds in the nitride film. Samples with stacks display excellent surface passivation following high-temperature forming gas anneals, indicating that such treatments can be used for photovoltaic applications, where surface passivation as well as good optical properties are important.