Remote Microwave Plasma Enhanced Chemical Vapour Deposition of Amorphous Carbon : Optical Emission Spectroscopy Characterisation of the Afterglow and Growth Rates

Amorphous carbon films were obtained by remote microwave plasma enhanced chemical vapour deposition (RMPECVD). In this process, a mixture of argon and hydrogen is excited in the microwave discharge while methane is injected in the afterglow. The substrates are radio-frequency (RF) biased in order to improve the film properties. Three configurations have been compared : microwave, RF, and mixed microwave-RF coupling. Optical emission spectroscopy allowed to compare intensities of a few spectral lines in the afterglow (CH, C2, H, and Ar lines) as a function of process conditions. Films have been characterised by infra-red (IR) spectroscopy and electron recoil detection analysis (ERDA). Stress in the films is in the range of -0.7 to -0.3 GPa (compressive). The influence of the hydrogen presence in the plasma, microwave pewer and radio-frequency bias voltage is discussed.