The interfacial adhesion energy was studied using the four-point bend method for boron carbo-nitride (BCxNy) deposited on dielectric and copper films. Twenty-five nanometer BCxNy films were deposited by chemical vapor deposition at 360 °C and 1 Torr using dimethylamine borane with no coreactant, NH3, or C2H4, producing different composition films, BC0.37N0.15, BC0.11N0.49, BC0.92N0.07, with dielectric constants of 4.1, 4.2, and 3.8, respectively. BCxNy films were deposited on dense and porous dielectrics, and copper. BCxNy films adhered strongly to the dielectric films and the composite beams snapped before debonding, revealing that the critical debond energy Gc exceeded 10 J/m2. The adhesion of BCxNy to oxidized copper increased with carbon content in the film, with the BC0.92N0.07 film beams snapping, and is possibly related to covalent bonding between surface oxygen and carbon in the film.