AbstractThe chemical stability of three heterosubstrates (Si, 3C-SiC and iridium) has been studied using the same MPCVD reactor during the successive steps of BEN process. An in situ sequential approach allows a monitoring of the chemical modifications induced by interactions between plasma and surfaces. Contrary to silicon, 3C-SiC and iridium underwent weak surface evolutions during BEN. This leads to favourable conditions for the interface formation in agreement with the better Highly Oriented Diamond films reported in the literature. A short description of the nucleation pathways identified for each heterosubstrate is also presented.