On periodic oscillations observed on cathode voltage and discharge current during HIPIMS process
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| Year of publication | 2014 |
| Type | Conference abstract |
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| Description | HiPIMS is promising technique for depositing thin layers. Instabilities accompanying HiPIMS also known as spokes were firstly observed independently by Anders et al and Kozyrev et al. Since then, OES and Langmuir probes are usually used for spoke diagnostics. In our research, periodic oscillations were not only observed on OES, but also on cathode voltage and discharge current. Alcatel SCM 650 sputtering system equipped with 20 cm titanium target and balanced magnetic field configuration was employed. Melec SIPP 2000 HiPIMS generator with maximum allowed voltage of 1000 V and maximum allowed current of 500 A was used. The generator was operated in constant voltage mode; discharge duration was 200 us with repetition frequency of 50 Hz. When the discharge current overreached typically 250 A, the periodic oscillations of discharge current and cathode voltage with frequency around 350 kHz were observed. Amplitude of the current oscillations was around 25 A, amplitude of the voltage oscillations was around 400 V. Varying discharge voltage different current time evolutions were obtained. However, the actual frequency of oscillations depended always on actual discharge current. This behavior is in contrary with behavior observed by Winter et al. With the increasing pressure the frequency of oscillations also increases. This result agrees with observations of Ehiasarian et al. Aforementioned results lead us to conclusion that observed oscillations of electrical quantities are another, yet not described manifests of the spoke phenomenon. |
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