Plasma Excitation Waveforms for Ion Energy Control in Etching

The patent applies periodic action by using pulsed voltage waveforms with specific duty cycles to control ion energy distribution. The waveform generator produces periodic pulses that accelerate ions in controlled bursts, creating distinct high-energy and low-energy ion populations that reach the substrate at different times, thereby achieving precise control over sheath properties and ion energies without excessive equipment complexity

The patent implements dynamics by making the voltage waveform adjustable and time-dependent. The waveform generator can dynamically change pulse width, amplitude, and duty cycle to optimize ion energy distribution for different processing conditions. This dynamic control allows adaptation of sheath properties and ion energies to specific etching requirements, resolving the contradiction between precision control and device simplicity

The patent applies segmentation by dividing the ion energy distribution into distinct segments or peaks. The pulsed waveform creates a first population of high-energy ions that etch deep into high aspect ratio features, and a second population of low-energy ions that perform gentle finishing. This segmentation of ion energies allows deep etching while minimizing mask sputtering and sidewall damage, as each ion population performs its specific function without causing harmful effects

The patent implements continuity of useful action by maintaining a continuous supply of ions to the substrate through repeated pulsed cycles. The waveform generator continuously produces pulses that deliver both high-energy and low-energy ion populations in sequence, ensuring that etching proceeds continuously without interruption. This continuous action maintains productivity for deep feature etching while the alternating high-low energy sequences prevent accumulation of damage effects