Deposition of microcrystalline silicon in electron-cyclotron resonance discharge (24 GHz) plasma from silicon tetrafluoride precursor

• The deposition of silicon films from silicon tetrafluoride with high rate is demonstrated.
• Silicon tetrafluoride is efficiently decomposed in plasma with gyrotron pumping.
• Gyrotrons extend the deposition pressure range to tens of pascals.

Deposition of Si films is done in a high power 24 GHz gyrotron-based electron-cyclotron resonance plasma enhanced chemical vapour deposition setup. The possibility of high-rate (2.5 nm/s) deposition of thin silicon films from SiF4 + H2 plasmas in an electron-cyclotron resonance reactor with gyrotron microwave plasma source at the frequency of 24 GHz is demonstrated. The analysis with spectroscopic ellipsometry and Raman scattering shows that films have large crystalline fraction (75%) with an average size of silicon grains of 3 nm. The use of gyrotron with high microwave power opens up the possibility to make depositions from high density plasmas at pressures of tens of pascals, which results in high deposition rates (tens nm/s).