Effect of higher-silane formation on electron temperature in a silane glow-discharge plasma

Electron temperature measured by an optical-emission spectroscopy shows a strong substrate temperature dependence in a silane glow-discharge plasma. The electron temperature increases with time after turning on the plasma at a low substrate temperature of 150 degreesC, while it stays constant at a high substrate temperature of 400 degreesC. The electron temperature is drastically reduced when the source gas silane is diluted with hydrogen at low substrate temperatures. These results suggest that the electron temperature in silane plasma is strongly affected by an electron-attachment process to higher-order silane molecules whose formation reactions show negative activation energies with gas temperature and are also suppressed by the presence of hydrogen molecules. (C) 2000 American Institute of Physics. [S0003-6951(00)04744-6].