Production of a uniform VHF H2 plasma by a narrow-gap discharge. (November 2015) - Lien, Cheng-Yang
Abstract: We produced a VHF H2 plasma (frequency, 60 MHz) by a narrow-gap discharge and examined the plasma parameters as a function of pressure and power, where two parallel plate electrodes (400 × 300 mm 2 ) were used. The plasma density reached a peak at a certain pressure, and when the power was increased, the peak pressure at which the density reached this peak shifted to higher pressures. Measured sheath potentials were lower than the theoretical values while the electron temperature was relatively high. An estimation of plasma uniformity was attempted by measuring the ion saturation current distribution, and the uniformity of about 4% was achieved. Highlights: A VHF H2 plasma is produced by a narrow-gap discharge. A narrow-gap VHF discharge provides a uniform high density plasma. The plasma density takes a peak at a certain pressure. Measured sheath potentials are lower than the theoretical values. Plasma uniformity of about 4% is achieved.