Apparatus and method for controlling plasma density profile

A method for controlling a plasma density profile relative to a substrate, comprising:

• applying radiofrequency (RF) power to a reactant gas to generate a plasma over a top surface of a substrate;
• controlling an amount of RF power transmitted through each of a plurality of RF power transmission paths, wherein the RF power transmission paths are spatially dispersed throughout the plasma relative to the top surface of the substrate, wherein controlling the amount of RF power transmitted through a particular RF power transmission path causes a plasma density within a vicinity of the particular RF power transmission path to be proportionally controlled;
• measuring a plasma density at various spatially dispersed locations over the top surface of the substrate;
• comparing the measured plasma densities to a target plasma density profile defined relative to the top surface of the substrate;
• and
• determining adjustments to the controlled amount of RF power transmitted through each of the plurality of RF power transmission paths as required to make a plasma density profile represented by the measured plasma densities substantially match the target plasma density profile.