Investigation of boron nitride films deposited by RF magnetron sputtering with in-situ spectroscopic ellipsometry and stress measurements

The present study is aimed at developing BN films deposited by rf magnetron sputtering and to determine the deposition conditions that result in stable, transparent and thick BN films for optical and high-temperature applications. The formation and kinetics of growth, the material properties and the optical properties of the films were examined in-situ and ex-situ by spectroscopic ellipsometry. The effect of bias voltage during deposition on both fundamental and Penn gap of the films was studied. Films deposited with negative bias voltages applied onto substrate are more transparent with larger fundamental and Penn gaps. Detailed stress measurements in the BN films were conducted with a laser cantilever technique by using two different lasers. Stress versus thickness curves show different behaviour between films deposited with positive and negative bias voltage. Moreover, X-ray reflectivity measurements were used in order to examine the density and the structural characteristics of BN films.