Thermal stability of Si₃N₄/Si/GaAs interfaces

An investigation on the thermally induced interface degradation of Si₃N₄/Si/p-GaAs metal-insulator-semiconductor (MIS) structures is presented. We characterize the mutation of chemical identities by in situ angle-resolved x-ray photoelectron spectroscopy and the nature of an insulator and interface by a variable angle spectroscopic ellipsometry after high temperature annealing. The minimum interface state density of the Si₃N₄/Si/p-GaAs MIS capacitor as determined by capacitance-voltage and conductance loss measurements was about 8 X 10¹⁰ eV^-1 cm^-2 near GaAs midgap after rapid thermal annealing at 550°C in N₂. However, this density increased to 5 X 10¹¹ eV^-1 cm^-2 after annealing at 750°C in N₂. The underlying mechanisms responsible for this degradation are described.