Intrinsic stress measured on ultra-thin amorphous carbon films deposited on AFM cantilevers

摘要

Ultra-thin amorphous carbon films were deposited onto atomic force cantilevers by plasma enhanced chemical vapour deposition. High magnification scanning electron micrographs at 30 kV reveal that the AFM tip is not affected by the deposition but its radius is broadened by the presence of the coating. Energy dispersive X-ray analysis at 4 kV shows that the film mostly coats one side of the lever, resulting in a bending of the cantilever, readily observable by scanning electron microscopy. This deformation is elastic and is caused by an internal compressive stress of 2.60 and 2.54 GPa, respectively, for 20-nm and 110-nm-thick films. After 15 at. percent Si incorporation, these stresses are reduced to 0.97 and 0.78 GPa. It is believed that the increased hydrogenation upon silicon addition causes a loosening of the carbon network structure and is, therefore, responsible for the observed stress relief.