Optical and physicochemical properties of hydrogenated silicon nitride thin films: Effect of the thermal annealing (original) (raw)

2017, Spectroscopy Letters

The effect of thermal annealing on the optical and physico-chemical properties of hydrogenated silicon nitride films was studied. These films were deposited by plasmaenhanced chemical vapor deposition from a mixture of silane, ammonia and nitrogen. Subsequently, the films were annealed at various temperatures ranging from 400 to 1000 degrees Celsius. The properties of the films were studied using ellipsometry and Fourier transform infrared spectroscopy. The Maxwell Garnet model considers the silicon nitride material as heterogeneous with three distinct phases: silicon, stoichiometric silicon nitride and hydrogen. Based on the ellipsometric analysis, the annealing treatment leads to reduce the volume fraction of both hydrogen and silicon. As a result, the stoichiometry parameter significantly increases from 1.24 to 1.32 making it closer to the stoichiometric silicon nitride one. According to the infrared data, a noticeable decrease in the total hydrogen concentration in the films was obtained with respect to the annealing temperature.