Effect of Radio-Frequency and Low-Frequency Bias Voltage on the Formation of Amorphous Carbon Films Deposited by Plasma Enhanced Chemical Vapor Deposition

• Published in: Plasma science & technology 2014-10, Vol.16 (10), p.954-959
• Main Authors: Manis-Levy, Hadar, Livneh, Tsachi, Zukerman, Ido, Mintz, Moshe H., Raveh, Avi
• Format: Article
• Language: English
• Subjects: Bias; Carbon; Deposition; Electric potential; Formations; Hardness; Hydrogen storage; 低频率; 偏置电压; 无线电频率; 等离子体发生; 等离子体增强化学气相沉积; 等离子体沉积; 结构变换; 非晶碳薄膜
• ISSN: 1009-0630
• DOI: 10.1088/1009-0630/16/10/09

The effect of radio-frequency （RF） or low-frequency （LF） bias voltage on the for- mation of amorphous hydrogenated carbon （a-C：H） films was studied on silicon substrates with a low methane （CH4） concentration （2-10 vol.%） in CH4＋Ar mixtures. The bias substrate was applied either by RF （13.56 MHz） or by LF （150 kHz） power supply. The highest hardness values （~18-22 GPa） with lower hydrogen content in the fihns （~20 at.%） deposited at 10 vol.% CH4, was achieved by using the RF bias, However, the films deposited using the LF bias, under similar RF plasma generation power and CH4 concentration （50 W and 10 vol.%, respectively）, displayed lower hardness （~6-12 GPa） with high hydrogen content （~40 at.%）. The structures analyzed by Fourier Transform Infrared （FTIR） and Raman scattering measurements provide an indication of trans-polyacetylene structure formation. However, its excessive formation in the films deposited by the LF bias method is consistent with its higher bonded hydrogen concentration and low level of hardness, as compared to the film prepared by the RF bias method. It was found that the effect of RF bias on the film structure and properties is stronger than the effect of the low-frequency （LF） bias under identical radio-frequency （RF） powered electrode and identical PECVD （plasma enhanced chemical vapor deposition） system configuration.