Boron-carbon-nitrogen films were grown by RF reactive sputtering from a B4C target and N-2 as reactive gas. The films present phase segregation and are mechanically softer than boron carbide films (a factor of more than 2 in Young's modulus). This fact can turn out as an advantage in order to select buffer layers to better anchor boron carbide films on substrates eliminating thermally induced mechanical tensions. (C) 2013 AIP Publishing LLC.