Growth and characterization of fluorocarbon thin films grown from trifluoromethane (CHF3) using pulsed-plasma enhanced CVD

Trifluoromethane (CHF3) was used as a precursor gas in pulsed-plasma enhanc ed CVD to deposit fluorocarbon films onto Si substrates. The film compositi on, as measured by X-ray photoelectron spectroscopy (XPS) of the C1s peak, was observed to change as the plasma duty cycle was changed by varying the plasma off-time; this offers a route to control the molecular architecture of deposited films. FTIR results indicate that the film is primarily compos ed of C-x, components, with little or no C-H incorporation into the film. T he rms roughness of the films is extremely low, approaching that of the Si substrate; the low growth rate and consequent high-power input/thickness is believed to be partly responsible. CHF3 produces films with higher % CF2 c ompared to other hydrofluorocompound (HFC) monomers (CH2F2 and C2H2F4). How ever, the deposition kinetics for all three HFC gases display similar trend s. In particular, at a fixed on-time of 10 ms, the deposition rate per puls e cycle reaches a maximum at an off-time of approximately 100 ms. (C) 2000 John Wiley & Sons, Inc.