Use of the hydrocarbon plasma of a low-pressure arc discharge for deposition of highly adhesive a-C:H films

It has been investigated whether a source of a hydrocarbon plasma generated by a non-self-sustained low-pressure arc discharge is suitable for production of highly adhesive a-C:H films. The distinguishing feature of this plasma source is the possibility for varying the degree of plasma ionization and the degree of destruction of hydrocarbon gases, making possible to realize both pure plasma-immersion ion implantation (PIII) and plasma-immersion ion deposition (PIID) in a unified vacuum cycle. The plasma parameters were measured with probes as functions of discharge current. Based on these measurements, the parameters of plasma generator have been determined for the PIII and PIID operation. The parameters of the pulsed bias voltage applied to the substrate in the process of the ion implantation and growth of an a-C:H film have also been preliminary chosen. For PIID it has been demonstrated that the improvements in quality of the a-C:H coating and in its adherence to the substrate are attained when an energy per carbon atom built in the coating is lying in the range 200–500 eV. The growth rates of a-C:H films in this case are approximately 200–300 nm/h. It was shown that the most favorable for achieving high energies per deposited carbon atom and for reducing of residual intrinsic stress are short (∼60 μs) high-voltage (>1 kV) substrate bias pulses.