Pulsed DC plasma CVD system for the deposition of DLC films

Abstract

Pulsed DC plasma chemical vapour deposition (CVD) system with a compact vacuum chamber has been developed using a simple configured pulsed DC power supply. Pulsed DC discharge was examined with variation of operation parameters as well as source gas materials. Diamond like carbon (DLC) films were deposited on silicon (Si) substrates from acetylene (C2H2) or carbon-monoxide (CO) at two distinct temperatures. The fabricated films were characterized by Raman spectroscopy, FTIR spectroscopy, and scanning electron microscopy (SEM). The results reveal that the films prepared from CO gas exhibited soft conductive DLCs with a large number of graphite like structures whereas mostly insulating hydrogenated amorphous carbon DLCs were obtained from C2H2 gas. The deposition rate from CO was lower than from C2H2 due to etching by oxygen produced from the source gas. As the substrate temperature increased, progressive graphitization was incorporated to the films deposited from both gases. By using the pulsed DC plasma CVD system, the energy efficiency for CVD as the ratio of growth volume to energy consumption was dramatically improved with some distinctive differences in film properties as compared to our previous RF plasma CVD. The results showed many advantageous features of pulsed DC plasma CVD for replacing conventional RF plasma CVD.