Geometric focusing technology applied to SiO2 etching

With the current downward trend in operating pressures, the role of ion and neutral densities in maintaining elevated etch rates has become increasingly important in the field of plasma dry etch. Many advanced source technologies have been developed that achieve higher densities and greater reagent production, but they often attain enhancements by imposing additional power requirements on an etch system. This article will show that in some advanced chamber designs, changes in electrode geometry can enhance ion density and/or dissociation and thus improve etch rate, without increasing the radio frequency power demand. The term ‘‘geometrical focusing’’ is used to describe the effects observed on a plasma after modifications were made to the grounded electrode of a commercial etch chamber. The improvements were recorded both in open areas and dense submicron contacts. In the future, more work is planned to investigate the effects of further modification to the focusing design, and more experimentation to det...