A New High-Power Density Tailored Waveform Modulator for Plasma Processing

A narrow plasma ion energy distribution (IED) is an important for improving the precision of plasma processes in semiconductor manufacturing. The tailored voltage waveform (TVW) based plasma processing has attracted significant attention as a monoenergetic IED can be achieved. Conventional TVW modulators need separate circuits to implement bias voltage and slope voltage, which results in a larger volume and the use of numerous switching components. In this article, a new high power-density TVW modulator is proposed, which reduces the volume and switching components by integrating the bias voltage modulator and the slope voltage modulator. The proposed modulator simplifies the circuit by integrating switches and offers an inherent inductor current bypass in case of fault situations, which removes the additional circuit. Furthermore, even when scaling up to a multimodal IED system using two or more negative bias voltages, inductor voltage swings due to bias voltage variations do not occur, resulting in a significant reduction in inductor volume. The feasibility of the proposed modulator was verified through a prototype targeting a total of 1.2 kV tailored voltage waveforms at 100 kHz, positive voltage bias of 400 V, negative voltage biases of -100 V/-500 V, and slope voltage of -300 V.