Study of spatial profiles of capacitively coupled VHF H2 plasma by simulation

• Published in: Japanese Journal of Applied Physics Vol. 56; no. 1S
• Main Authors: Chen, Kuan-Chen, Chiu, Kuo-Feng, Ogiwara, Kohei, Su, Li-Wen, Uchino, Kiichiro, Kawai, Yoshinobu
• Format: Journal Article
• Language: English
• Published: The Japan Society of Applied Physics 09.11.2016
• ISSN: 0021-4922; 1347-4065
• DOI: 10.7567/JJAP.56.01AC05

The spatial profiles of a VHF H2 plasma (60 MHz) for different discharge gap distances were examined at pressures of 66.7 and 133.3 Pa by two-dimensional simulations using the plasma hybrid code. The electron density had a peak profile, and the maximum density depended on both the discharge gap distance and the pressure. A high-electron-density plasma with a low-electron temperature of approximately 1 eV was predicted by simulation at discharge gap distances of 15 and 20 mm. The plasma potential profile was composed of a plateau at the center and sharp slopes at the two sides. The axial profiles of the H+, H2+, and H3+ densities were calculated for the discharge gap distances of 10, 15, and 20 mm. It was found that the dominant ion species was H3+ except near the discharge electrode and the H2+ density near the discharge electrode was not negligible compared with the H3+ density at 66.7 Pa.