We have developed a lowhyphen;temperature (lsim;300thinsp;deg;C) plasma deposition process to prepare novel fluorinehyphen;containing silicon nitride films (phyphen;SiN:F) using SiH4ndash;NF3ndash;N2discharge mixtures at 14 MHz rf applied frequency. The deposition rate can be extremely high, up to 1600 Aring;/min. Data indicatephyphen;SiN:F has electrical properties (dielectric constant, breakdown strength, resistivity, etc.) which compare favorably to highhyphen;temperature, chemicalhyphen;vaporhyphen;deposited silicon nitride. By controlling the feed chemistry and physical variables of the discharge, a wide variety of film compositions are achieved. Moreover, this chemistry is superior to the only otherphyphen;SiN:F which was prepared from a SiF2/SiF4hyphen;H2hyphen;N2feed. Two classes of films were identified as stable or unstable to air exposure and the instability of the films correlated with the atom fraction of fluorine initially incorporated. Infrared, Auger electron, and Rutherford backscattering spectroscopy measurements show that low hydrogen concentrations are produced by the introduction of fluorine in the silicon nitride films. More importantly, the concentration of Sindash;H is extremely low because strong Sindash;F bonding replaces the weak Sindash;H bonds that satisfy free Si orbitals found in conventional plasma nitride, and the hydrogen remaining in the film is present as stable Nndash;H bonds. We believe this substitution of siliconhyphen;bound hydrogen, caused by the gas phase and surfacehyphen;driven reactions, is a source of superior film properties. The mechanism for this novel discharge chemistry is discussed.
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