The growth of silicon nitride crystalline films using microwave plasma enhanced chemical vapor deposition

Crystalline thin films of silicon nitride have been grown on a variety of substrates by microwave plasma-enhanced chemical vapor deposition using N2, O2, and CH4 gases at a temperature of 800 °C. X-ray diffraction and Rutherford backscattering measurements indicate the deposits are stoichiometric silicon nitride with varying amounts of the a and β phases. Scanning electron microscopy imaging indicates β—Si3N4 possesses sixfold symmetry with particle sizes in the submicron range. In one experiment, the silicon necessary for growth comes from the single crystal silicon substrate due to etching/sputtering by the nitrogen plasma. The dependence of the grain size on the methane concentration is investigated. In another experiment, an organo-silicon source, methoxytrimethylsilane, is used to grow silicon nitride with controlled introduction of the silicon necessary for growth. Thin crystalline films are deposited at rates of 0.1 μm/h as determined by profilometry. A growth mechanism for both cases is proposed.