Highly-resistant SiCBN films prepared by a simple spin-coating process with poly(borosilazane)

Abstract

Amorphous silicon–carbon–boron–nitrogen (SiCBN) ceramic films, stable at high temperatures, were prepared by spin-coating Si or SiO₂/Si substrates with poly(borosilazane) solution under different conditions, followed by pyrolysis at 900–1100 °C. A range of film thicknesses of 100–500 nm was achieved by varying the concentration of the polymeric solutions. SEM and AFM micrographs of the films exhibited a crack-free, fairly smooth and dense surface morphology with an average roughness of 2–4 Å. The surface hardness and elastic modulus of the SiCBN films were found, by nanoindentation measurement, to be 7.48 GPa and 65.65 GPa, respectively. AES analysis of the SiCBN films revealed a homogenous composition with a Si : B ratio of ∼2.4. In particular, the SiCBN films pyrolyzed at 900 °C exhibit extraordinary stability under isothermal oxidation at 1000 °C for 8 h in air with a resulting mass loss of only 0.1%. In addition, the SiCBN film pyrolyzed at 900 °C under vacuum acts as an electrical insulator, exhibiting a sheet resistance of 10¹⁴ Ω cm⁻² at room temperature.