Application of direct bias control in high-density inductively coupled plasma etching equipment

Abstract

The use of a novel method of power delivery control at the wafer chuck in a high-density inductively coupled plasma reactor has been investigated. This method involves using a peak voltage sensor mounted immediately below the chuck in a feedback loop to the rf generator such that the rf peak voltage can be set as a recipe parameter. By controlling the power delivery in this manner, it is demonstrated that the effects of power losses in the rf circuit between the generator and the chuck, especially in the match network, can be compensated for. In addition, the effect of interactions among source power, bias power and other process parameters on sheath voltage can also be eliminated. In this manner a more complete decoupling of plasma density and ion energy can be achieved than more conventional methods of power delivery allow.