FLUOROHYDROGENATED AMORPHOUS-CARBON (A-C-H,F) FILMS PREPARED BY THE RF PLASMA DECOMPOSITION OF 1,3-BUTADIENE AND CARBON TETRAFLUORIDE

Amorphous fluorohydrogenated carbon films (a-C:H, F) were prepared by the r.f. glow discharge decomposition of a hydrocarbon (C4H6) diluted with a fluorocarbon (CF4). An increase in the CF4 content of the deposition gas mixture was accompanied by a corresponding increase in the fluorine content and a decrease in the hydrogen content of the films. The IR spectra indicate fluorine incorporation in the film primarily via the monofluoride mode. No absorption owing to CF2 and CF3 could be detected. The film density and optical bandgap stayed fairly constant until about 40-50% dilution with CF4. Further dilution of the hydrocarbon with CF4 resulted in a large drop in the deposition rate, film density, optical bandgap, oxygen plasma etch resistance and thermal stability. These film properties differ from those of a-C:H, F films obtained by the r.f. plasma decomposition of substituted benzenes (Sah et al., Appl. Phys. Lett., 46 (1992) 739).