Diamond-like carbon films with low internal stress by a simple bilayer approach

Abstract

Amorphous carbon films with a high hardness usually suffer from high internal stress. To deposit films with a hard top surface but reduced internal stress, a simple bilayer approach was used. Films were prepared by plasma source ion implantation, using only hydrocarbon precursors. The single layer with the highest hardness (deposited by a low direct current (DC) voltage and radio frequency (RF) generation of the plasma) has the highest internal stress with more than 3.5 GPa. By adding an interlayer with a lower hardness, the resulting stress of the bilayer film can be reduced to below 1.4 GPa while maintaining the high hardness of the top layer. By avoiding metallic interlayers or dopants within the films, the deposition process can be kept simple and cost-effective, and it is also suitable for three-dimensional samples.