Structural Properties of Ultrathin Amorphous Silicon Oxynitride Layers

7-nm-thick amorphous silicon oxynitride (a-SiOxNy) layers were prepared at 300°C using a plasma nitridation technique on different types of crystalline Si substrates and under different ammonia flow rates, [NH3]. The compositional and structural properties of the a-SiOxNy layers were examined using current–voltage (I–V), capacitance–voltage (C–V), electron spin resonance (ESR), Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) measurements. A strong correlation between the changes in the I–V, C–V characteristics and in the ESR spin density (Ns) was obtained. The use of low-resistivity Si substrates enabled us to assess simultaneously the changes in the defect density and the electrical properties. Based on the FT-IR results, the changes in the 800 and 1070 cm-1 absorption bands are discussed in connection with the structural change.