High-Power Pulsed Magnetron Sputtering Glow Plasma in Argon Gas and Pulsed Ion Extraction

Plasma-ion processing enhances the functionality of a film, and as such, metal plasma sources are indispensable in film preparation. A magnetron sputtering glow plasma is generated by a pulsed power source in a process called a high-power pulsed magnetron sputtering glow plasma. Metal species are sputtered by energetic argon ions and are ionized. Ions are extracted from the plasma when a substrate holder electrode (SHE) is immersed in the plasma. This process has been referred to as plasma-based ion implantation and deposition (PBII&D). This paper deals with the electrical and optical characteristics of a pulsed magnetron sputtering glow plasma in which pulsed ion extraction is carried out by the PBII&D method. Work is presented showing that the voltage and current characteristics can be represented as a series connection of voltage source, current-limiting resistor, and plasma impedance. As a result, the characteristics are normalized by the peak current and the maximum power consumed in the plasma where a circuit-matching condition is satisfied. However, when the temporary behavior of the current changes by over 20 A/μs under the experimental conditions, a circuit inductance originating from the connecting wire in the circuit can significantly influence the electrical characteristics. As a result, the peak current and the maximum consumed power cannot be used to normalize the electrical characteristics. When an inductive component is considered, the electrical characteristics obtained experimentally are curve fitted to the calculated values. Ion extraction from the glow plasma was successfully observed. This suggests that the PBII&D method can be employed in the case of a high-power pulsed glow plasma. The waveform of the extracted ion current is seen to have a sharp peak at the initial stage of voltage application to the SHE, followed by a stationary state. This confirms that the SHE is immersed in the plasma. The plasma density is on the order of 10
¹⁷
m
^-3
and is estimated by the recovery characteristics of the voltage applied to the SHE. The ion density of the glow plasma is found to be proportional to the extracted stationary ion current at the end of the pulse applied to the SHE. The temporary behavior of the optical emission spectrum of the glow plasma confirms that sputtered titanium species are ionized to a singly ionized state and that their appearance is delayed from the appearance of argon ions.