Deposition of hydrogenated amorphous carbon films by CH₄/Ar capacitively coupled plasma using tailored voltage waveform discharges

Abstract

We investigated effects of tailored voltage waveform (TVWs) discharges on deposition of hydrogenated amorphous carbon (a-C:H) films in CH4/Ar capacitively coupled plasma. TVWs discharges employ two driving radio frequencies (13.56 MHz and 27.12 MHz) and control their phase shift to independently regulate ion bombardment energy (IBE) and ion flux. In this study, a-C:H films were deposited by changing DC-self bias with phase shift and constant applied voltage peak-to-peak. Additionally, we investigated phase resolved optical emission spectroscopy (PROES) for plasma characterization. As a result, plasma enhanced chemical vapor deposition (PECVD) for a-C:H films using TVWs discharges realize control of film properties such as mass density, sp3 fraction and H content, with keeping deposition rate constant. Thus, it is suggested that TVWs discharges realize the independent control of IBE and ion flux with high accuracy, highlighting its utility in a-C:H film depositions.