Plasma Bias Waveform Generator Using Resonant Multi-Level Commutation

The patent applies periodic pulsed voltage waveforms to the substrate electrode, creating alternating discharge and non-discharge periods. This periodic action allows the plasma sheath to form and collapse cyclically, enabling ion energy control while reducing average power loss compared to continuous DC operation. The pulsed nature of the waveform reduces commutation losses by limiting the time during which high voltage and current coexist.

The patent changes the voltage waveform parameters (amplitude, pulse width, frequency, shape) to optimize the balance between ion energy distribution and commutation losses. By adjusting these parameters, the system can achieve desired ion energy control while minimizing energy loss during voltage transitions. The ability to independently control multiple waveform parameters provides fine-tuned optimization of the contradiction between loss reduction and process effectiveness.

The patent applies preliminary damping actions during the voltage transition phases to prevent resonance excitation before it can develop into harmful ringing. By incorporating damping resistance or snubber circuits that activate during switching transitions, the system preemptively dissipates energy that would otherwise excite the LC resonance, allowing faster switching without the harmful effects of resonance.

The patent converts the potentially harmful resonance effect into a beneficial by utilizing controlled damping during switching transitions. The damping resistance, while causing some energy loss during switching, prevents much larger losses from uncontrolled resonance ringing during the discharge period. This transforms the harmful resonance phenomenon into a controllable parameter that can be managed to achieve overall system optimization.

The damping resistance is activated periodically only during voltage switching transitions rather than continuously during the entire discharge period. This periodic activation allows the damping element to suppress resonance ringing at critical moments while remaining inactive during the main discharge period, thereby minimizing energy loss. The pulsed nature of damping activation reduces overall energy consumption compared to continuous damping.

The patent applies partial damping action only during the critical switching transition phases rather than full continuous damping. This partial action is sufficient to prevent resonance excitation at the moments when it is most likely to occur, while avoiding the excessive energy losses that would result from continuous damping throughout the entire operating cycle. The damping is applied just enough to prevent harm without over-damping the system.

The patent employs periodic pulsed voltage waveforms that can be generated more efficiently than continuous waveforms. The pulsed nature allows the amplifier to operate in switching modes rather than linear modes, improving efficiency while maintaining waveform flexibility. The periodic discharge periods allow the amplifier to reset and prepare for the next pulse, enabling efficient operation across a wide range of waveform parameters.

The patent utilizes variable waveform parameters (amplitude, pulse width, frequency, shape) that can be adjusted to optimize both flexibility and efficiency. By changing these parameters, the system can adapt to different process requirements while operating in efficient switching modes rather than continuous linear modes. The ability to independently control multiple parameters provides versatility without sacrificing efficiency.