Production of a uniform VHF H2 plasma by a narrow-gap discharge

• Published in: Vacuum Vol. 121; pp. 289 - 293
• Main Authors: Lien, Cheng-Yang, Chen, Chia-Fu, Yang, Ching-Lung, Kawai, Yoshinobu, Chiu, Kuo-Feng, Shi, Jen-Bin, Wang, Jui-Hao, Lien, Shui-Yang, Tsai, Yu-Jer, Lien, Ting-Kuei
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2015
• Subjects: High pressure depletion method; Microcrystalline silicon films; Narrow-gap discharge; Sheath potential; VHF plasma; High pressure depletion method; Narrow-gap discharge; Microcrystalline silicon films; VHF plasma; Sheath potential
• ISSN: 0042-207X; 1879-2715
• DOI: 10.1016/j.vacuum.2015.02.037

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 mm2) 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. •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.