Low pressure pulse-modulated and radio-frequency plasma for CF4 decomposition

The CF₄ is one of the most stable gases among perfluorocarbons (PFCs) and their decomposition is extremely difficult. In this study, the CF₄ decomposition was investigated using the pulse-modulated and radio-frequency (RF) plasma of 2 MHz, which is applicable for plasma etching and novel functional material manufacturing processes. When the absolute pressure, the flow rates of 100 % CF₄ and 99.5 % O₂ were set at 80 Pa, 0.1 and 0.2 NL/min, respectively, almost complete CF₄ decomposition was achieved at the range of 25 kHz to 99 kHz of the pulse modulation frequency. The byproduct analysis in CF₄ decomposition was carried out using a CO₂ gas analyzer and a Fourier transform infrared spectrophotometer (FTIR) when the pulse modulation frequency was set at 75 kHz. It was known that 10%, 50% and 24% of CF₄ were converted to CO, CO₂ and COF₂, respectively. It was considered that the remaining 16% of carbon was converted to carbon particle or other organic substances.