Nested RF Pulsing for Uniform Semiconductor Plasma Processing

The patent applies periodic pulsed RF power instead of continuous RF power to the plasma generation system. The RF clock is pulsed at specific frequencies to generate plasma only during required intervals, creating periodic plasma generation cycles. This periodic action allows plasma to be generated efficiently when needed while preventing excessive ion accumulation that causes charging damage, thus resolving the contradiction between plasma generation efficiency and charging damage reduction.

The patent employs dynamic control of RF power delivery through adjustable pulsed frequencies and variable pulse widths. The system can dynamically modify the RF clock frequency and pulse characteristics in real-time based on processing requirements. This dynamic capability allows optimization of fast ON-OFF pulsing parameters to reduce charging damage while simultaneously maintaining plasma processing uniformity across the wafer surface.

The patent segments the RF pulsing control into multiple independent frequency layers: fast ON-OFF pulsing frequency for charging damage control and slow pulsing frequency for uniformity control. By segmenting the control frequencies and allowing independent optimization of each layer, the system achieves both high etch rate (through appropriate fast pulsing parameters) and processing uniformity (through coordinated slow pulsing parameters), resolving the contradiction between uniformity and productivity.

The patent merges the RF clock generation, pulsing control, and plasma generation functions into a single integrated matchless plasma source. The RF clock generator and pulsing control circuitry are embedded directly within the plasma source structure, eliminating the need for separate external matching networks and control systems. This merging reduces overall system complexity while maintaining precise plasma processing control through the integrated design.