Ion bombardment measurements and simulations of a low temperature VHF PECVD SiH4-H2 discharge in the a-Si:H to μc-Si:H transition regime

We studied ion bombardment during amorphous silicon layer deposition for hydrogen dilutions 5 to 59 with mass resolved IED measurements and simulations. The trends in the peak position of H2+ and SiHy+ IEDs with increasing hydrogen dilution show good agreement between measurements and simulations. A difference in asymmetry of the discharge between simulations and measurements results in a roughly 6 eV lower peak position for the simulations. An increasing SiHy+ ion flux with increasing hydrogen dilution is measured. We hypothesize that this is due to amorphous silicon etching that is enhanced by Hy+ ion bombardment.