Effects of Pressure and Electrode Length on the Abatement of N2O and CF4 in a Low-Pressure Plasma Reactor

The emission of greenhouse gases, such as N 2 O and fluorinated gases, has been increasingly regulated in the semiconductor industry. Pressure effects on the abatement of N 2 O and CF 4 were investigated in a low-pressure plasma reactor by using Fourier transform infrared (FTIR) spectroscopy. The destruction and removal efficiency (DRE) of N 2 O and CF 4 was significantly lowered below 0.2 Torr. When the pressure was increased, the DRE of CF 4 with H 2 O as the reactant gas increased continuously, but that with O 2 or without any reactant gas first increased and then decreased. A larger electrode length yielded a higher DRE of N 2 O and CF 4 , especially at lower pressures. To understand this phenomenon, the electrical waveforms for the discharge in N 2 O were analyzed in conjunction with its optical emission profiles, and the rotational temperatures for different electrode lengths were compared using the N 2 + ion band (λ = 391.4 nm). They provided insights into the mechanism involved in terms of plasma property and gas residence time.