Pulsed Ion Extraction from Shunting Arc Assisted Burst RF (195 kHz) Plasma

Abstract

Summary form only given. A burst RF (radio frequency, 195 kHz) inductively coupled plasma in a methane circumstance is generated with assistance of a pulsed carbon shunting arc discharge. The shunting arc is a metallic/semi-metallic plasma source without any trigger sources, and is ignited synchronously with the RF burst signal. The RF plasma was ignited at a methane pressure higher than 0.05 Pa and even in the vacuum, although the burst RF plasma is ignited at a pressure higher than 1.2 Pa in the absence of the shunting arc triggering. This hybrid plasma generation system is suitable for plasma-based ion implantation and deposition (PBII&D) to synthesize various compounds by combining gaseous species generated by the RF plasma with metallic species generated by the shunting arc discharge plasma. The emission spectra from the RF plasma, the shunting arc and their hybrid plasma were observed. When only the shunting arc is ignited, carbon spectrum at a wavelength of 426.7 nm significantly appears, and changes temporally with the behavior of the shunting arc current. For the hybrid plasma of the shunting arc and RF plasma, CH spectrum with a wavelength of 431.4 nm is observed in addition to the carbon spectrum. The ion density at the target immersed in the plasma is estimated by the ion sheath resistance. It is confirmed that the shunting arc enhances the ionization and excitation of methane particles. For the hybrid plasma of RF and shunting arc discharge, the plasma density is in a range of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sup> to 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> , which is higher by a factor of approximately 10 than that of the shunting arc discharge. Being proportional to the plasma density, the ion current extracted from the hybrid plasma becomes higher than that from each plasma, where a target with a diameter of 80 mm is immersed in the plasma by applying a train of pulsed voltage