DLC films were deposited on Si(111) substrates using CH₄/Ar gas and microwave ECR plasma CVD processes. The energy of the ions impinging on the substrate during deposition was varied by changing the rf self bias voltage developed on the substrate. The bonding characteristics of the deposited films were investigated using FTIR and Raman spectroscopy,and mechanical properties were measured by nanoindentation and nanoscratch tests. The results obtained from different characterization techniques are correlated and explained on the basis of existing growth models for DLC films. Our studies indicate that the energy of the ions impinging on the substrates has a strong influence on the bonding characteristics and mechanical properties of the films.