Shape Matters – Bipolar Sputtering
The possibility to increase the productivity of the deposition process is one of the most important factors for industry. One of the method to achieve this goal is the use the most up-to-date technique for delivery of power and control of the plasma discharge. In this paper two features of Bipolar power supplies were presented: (i) wide pulsing frequency range (up to 100 kHz), and (ii) an additional Brake Time between the positive and negative half-wave of the rectangular waveform of current and voltage. Both features have demonstrated their strong potential in the stabilization of the reactive sputtering by reducing the tendency of arcing. It was shown that doubling the standard operation frequency to 80 kHz allowed to keep the process stable even in the poisoned mode. On the other hand a significant reduction of arcing was also possible at lower bipolar pulsing frequency (40 kHz) if the output voltage and current waveform is modified by a Brake Time between the positive and negative half-wave. Therefore, a combination of higher pulsing frequency and additional Brake Time with fast and accurate arc detection mechanisms can be used as powerful method of sputtering process optimization.