New radio frequency technique for deposition of hard carbon films

We have developed a new technique to produce diamondlike carbon films in an rf system with water‐cooled electrodes. Hydrocarbon gas is leaked into the experimental chamber through the upper electrode which is a Pyrex cylinder inside a coil forming an rf oven. The gas (CH4) undergoes ionization/dissociation in one rf field, within an axial magnetic field. A circular water‐cooled electrode supports the substrate to be coated, and is powered from a second rf generator, developing a negative self‐bias on the substrate. Thus dissociation and ion production at the upper electrode and ion acceleration by the lower electrode could be separately controlled to optimize the film properties. It is shown that low stress, highly dense carbon films can be deposited by this method. Information is also given on bulk and surface properties as well as modification of these properties by the deposition conditions.