Pulsed voltage waveform biasing of plasma with multiple radio frequency generators

Abstract

Techniques and apparatus for waveform generation. The method generally includes generating an asymmetric radio frequency (RF) pulsed waveform by (i) delivering a first RF waveform at a first frequency using a first RF generator, (ii) delivering a second RF waveform at a second frequency using a second RF generator, (iii) delivering a third RF waveform at a third frequency using a third RF generator, and (iv) synchronizing the delivering of the first, second, and third RF waveforms by aligning the phases of the first, second, and third RF waveforms. The first frequency is generally greater than the second frequency, and the second frequency is generally greater than the third frequency. The first frequency is generally a first harmonic of a fundamental frequency of the asymmetric RF pulsed waveform, and the second RF waveform and the third RF waveform are generally higher harmonics of the asymmetric RF pulsed waveform.

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