Source RF Generator

Source and bias RF generators are the two independent power supplies that give a modern plasma reactor separate control over plasma density and ion energy — the source generator sustains the plasma itself, while a separate bias generator controls how hard ions are accelerated into the wafer, decoupling two variables a single-generator system can't adjust independently.

This decoupling is exactly what separates a modern ICP-style reactor from a simple parallel-plate CCP tool, and it's the real reason source/bias architecture became standard for demanding etch and deposition steps. In a single-generator CCP reactor, plasma density and the DC bias that accelerates ions are both consequences of the same RF power — turning that power up to increase density also turns up ion energy, whether the process wants that or not. A separate bias generator applied specifically to the chuck lets an engineer tune source power for the density a process needs and tune bias power for the ion energy it needs, as two genuinely independent knobs.

Bias power frequency choice adds another layer of control, since lower-frequency bias tends to accelerate ions more directly while higher-frequency bias affects the plasma sheath differently. Fabs often run bias at a lower frequency than source power specifically because lower-frequency bias couples more directly to ion acceleration across the sheath, giving a more direct handle on ion energy distribution — which is part of why multifrequency and dual-frequency bias schemes exist as their own engineering area within RF power delivery.

Source and bias RF generators together give a plasma process the two independent control variables that matter most — how much plasma there is, and how hard its ions hit the wafer — and that decoupling is foundational to essentially every modern, precisely-tuned etch and deposition process running in production today.