CVD of hard DLC films in a radio frequency inductively coupled plasma source

Chemical Vapor deposition (CVD) of hard diamond-like carbon (DLC) films on silicon (100) substrates from methane was successfully carried out using a radio frequency (r.f.) inductively coupled plasma source (ICPS). Different deposition parameters such as bias voltage, r.f. power, gas flow and pressu re were involved. The structures of the films were characterized by Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy. The hardnes s of the DLC films was measured by a Knoop microhardness tester. The surfac e morphology of the films was characterized by atomic force microscope (AFM ) and the surface roughness (R,)was derived from the AFM data. The films ar e smooth with roughness less than 1.007 nm. Raman spectra shows that the fi lms have typical diamond-like characteristics with a D line peak at similar to 1331 cm(-1) and a G line peak at similar to 1544 cm(-1) and the low int ensity ratio of I-D/I-G indicate that the DLC films have a high ratio of sp (3) to sp(2) bonding, which is also in accordance-with the results of FTIR spectra. The films hardness can reach approximately 42 GPa at a comparative ly low substrate bias voltage, which is much greater than, that of DLC film s deposited in a conventional r.f. capacitively coupled parallel-plate syst em. It is suggested that the high plasma density and the suitable depositio n environment (such as the amount and ratio of hydrocarbon radicals to atom ic or ionic hydrogen) obtained in the ICPS are important for depositing har d and high quality DLC films. (C) 2001 Elsevier Science B.V. All rights res erved.