Critical Level of Nitrogen Incorporation in Silicon Oxynitride Films: Transition of Structure and Properties, Toward Enhanced Anticorrosion Performance

Silicon oxynitride (SiOxNy) thin films are widely encountered in today's major key enabling technologies. Exhibiting tunable properties dependent on the nitrogen content, they attract attention in applications requiring thermal stability, high dielectric constant, corrosion resistance, surface passivation, and effective ion diffusion barrier. Identification of the minimum desired level of nitrogen incorporation for each application is important for simultaneously optimizing material properties and the deposition process. In this context, we study the structural and functional properties of SiOxNy films deposited from tris(dimethylsilyl)amine (TDMSA), O-2, and NH3, using conveniently scalable atmospheric pressure chemical vapor deposition (CVD) at moderate temperature (600-650 degrees C). A suite of characterization techniques including spectroscopic ellipsometry (SE), Fourier-transform infrared spectroscopy (FT-IR), ion beam analyses (IBA), nanoindentation, nanoscratch, X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM), water wettability, surface roughness, and resistance to wet etching corrosion are implemented in order to establish the relevant structure-composition-properties correlations. The produced SiOxNy films are smooth and amorphous, exhibiting beyond state-of-the art corrosion resistance in standard though particularly aggressive hydrofluoric buffer oxide etchant (BOE) 6:1 solution, with remarkable near-zero etching rate values. Compositional trends reveal the presence of C and H atoms, yet their incorporation has insignificant effect on the films RMS roughness and wet etching corrosion resistance. Coupled SE, FT-IR, and XPS analyses reveal that the SiOxNy network appears to undergo a sharp transition between 4 and 6 atom % N, affecting hardness and Young's modulus. Globally, material properties such as scratch resistance, surface roughness, and corrosion resistance are improved with increasing nitrogen content. Additionally, the asymmetric stretching silicon nitride (Si3N4) FT-IR absorption at ca. 850 cm(-1) is used to track the binding configuration in the amorphous SiOxNy network. Correlation of the elemental environment and chemical bonding to the corresponding process conditions can aid in identifying the process margins for desired intrinsic and/or functional properties.