In-situ monitoring of electron cyclotron resonance plasma chemical vapour deposition of hydrogenated silicon nitride films

Hydrogenated silicon nitride (SiN:H) films were deposited by electron cyclotron resonance plasma chemical vapour deposition on Si and InP substrates. A non-corrosive organic compound, liquid at room temperature and stable in air, CONSI™ 4000 (SiH2(C4H9)2), was used as the precursor for the silicon. Depositions were successfully made at relatively low substrate temperatures, below 300°C. The effects of the processing conditions on the plasma characteristics and film properties were investigated. The emission intensities from excited species in the plasma were monitored by optical emission spectroscopy. The corresponding electron temperature and the plasma density were determined by analysing the current-voltage characteristics of a Langmuir probe. The resulting film composition was determined by Auger electron spectroscopy. The combined in-situ methods facilitate optimization of the deposition conditions, eventually leading to stoichiometric films (Si-to-N ratio, about 0.75) with less than 2 at. % of incorporated carbon.