Material and tribological properties of a-C:H film by plasma CVD for a disk overcoat

Amorphous hydrogenated carbon (a-C:H) film deposited by plasma chemical vapor deposition (PCVD) using toluene as a monomer is durable enough for a very thin magnetic disk overcoat. In this paper, we discuss the effect of deposition conditions on material and mechanical properties of this film. Lowering deposition gas pressure increases the amount of sp/sup 3/ bonded carbon and the hardness, and decreases the hydrogen content of the film. Increasing bias voltage leads to the same effects. Properties of a PCVD film could be well controlled by the hydrogen content besides the amount of sp/sup 3/ bonded carbon. PCVD films were more durable than sputtered a-C:H films of less than 10 nm thickness. A PCVD film enables us to reduce disk overcoat thickness.