Pulsed DC Power Supplies for Dual Magnetron Sputtering

Key features of this waveform are the voltage boost period following each polarity transition and fast current rise time due to that boost. Ideally, the boost voltage would be adjustable. It is expected that adjusting the boost voltage will enable some tuning of the film properties, since it will effectively allow tuning of ion energy within the process. Additionally, adjustable duty, the ratio of positive to negative pulse width, would allow more power to be delivered to one of the magnetrons when desired. For flexibility, the DC power supply function is separated from the pulse function. As will be described later, this allows tremendous flexibility in configuration and power granularity. A block diagram of the simplest pulsed current supply system is shown in Figure 3, depicting the power flow from 3 phase mains power to the plasma load. The system consists of two key components: The AC mains are rectified and output voltage and current regulated to deliver the desired power utilizing a DC power supply that has the ability to communicate with the bipolar accessory. Output of the DC power supply is connected to the input of this bipolar accessory.