DEPOSITION AND CHARACTERIZATION OF DENSE AND STABLE AMORPHOUS HYDROGENATED BORON FILMS AT LOW SUBSTRATE TEMPERATURES

Amorphous hydrogenated boron (a-B:H) thin films were prepared by radio -frequency plasma chemical vapor deposition of B2H6 diluted in hydroge n. The influence of deposition parameters on chemical composition and structural properties were determined by ion beam analysis, Fourier tr ansform infrared (FTIR), X-ray photoelectron (XPS) and thermal desorpt ion (TDS) spectroscopy. FTIR and XPS analysis show differences in film stability depending on ion energy. Films deposited at low substrate t emperatures and low ion energies undergo chemical changes when exposed to atmosphere. XPS and FTIR revealed that these chemical changes are accompanied by an incorporation of carbon and oxygen into the bulk of the film. Stable films were prepared at substrate temperatures as low as 330 K if the ion energy is sufficiently high (self-bias voltages > 150 V). No chemical changes of these films were observed after 15 mont hs of exposure to ambient atmosphere. Chemical stability correlates wi th boron density which lies between 1.6-1.85 g/cm(3) for stable films.