Boron carbonitride thin films by PACVD of single-source precursors

This work investigates the influence of the carrier gases N-2, Ar, and He and the influence of the applied power density (about 1-4 W/cm(2)) on the chemical composition of boron carbonitride films deposited by a PACVD process. The plasma is activated via 13.56 MHz radio frequency. Si(100) wafers were used as substrates and pyridine-borane (PB) and triazaborabicyclodecane (TBBD) as B-C-N-forming single-source precursors. Films that were either deposited in He using a low power density or in N-2 using a high power density showed comparable properties. Analysis of these films showed their chemical composition to be BC4N. Moreover, they exhibited outstanding hardnesses of up to 64 GPa. A simple model describing the acceleration of B, C, and N ions in the plasma towards the substrate showed comparable ion moments by use of the corresponding deposition parameters. Basically, it was found that, the higher the ion momentum, the higher the film hardness.