The optical constants of boron nitride (BN) films on Si substrates were systematically investigated using spectroscopic ellipsometry. BN films with a wide variety of atomic compositions (B/N ratios) and bonding phases (sp2/sp3 ratios) were synthesized using a reactive plasma-assisted coating method, which consists of magnetically confined vacuum-arc discharge and electron-beam evaporation. A wide range of optical constants were assigned to various BN films via a model fitting procedure employing the Tauc–Lorentz optical model. The estimated film thicknesses corresponded with those determined using scanning electron microscopy. The optical constants of the films were found to be significantly dependent on their respective atomic compositions, which shows a transition from the semiconducting to the insulating phase in BN films in response to the deposition conditions. Ion bombardment during the film growth induced an increase in the refractive index along with an increase in the amount of the sp3 phase. Furthermore, the extinction coefficient increased substantially in the ultraviolet region in response to the generation of defects in the BN nano-network structures.

Boron nitride (BN) films with a wide variety of nano-network structures (sp2–sp3 bonded) were prepared and their sputtering behaviors were investigated. BN films were formed using a reactive plasma-assisted coating technique. Fourier transform infrared spectroscopy (FT-IR) and nanoindentation analyses confirmed the presence of sp2- and sp3-bonded phases. Then, the thickness change by plasma exposure was studied for various BN films. Sputtered depth after the plasma exposure of the prepared BN films was lower than that of SiO2 films. While no clear change was observed in the FT-IR spectra after the plasma exposure, the leakage current and dielectric constant changed due to the surface modification. It was found that the modified layer underneath the sputtered surface contained the local defects which play a role as carrier trapping or hopping sites. The sputtering behavior analysis in combination with electrical measurements is a useful methodology for designing BN films.