US Patent 7135410 Etch with ramping

A method for etching a feature in an etch layer through a mask over a substrate. The substrate is placed in a process chamber. An etch plasma is provided to the process chamber, where the etch plasma begins to etch. A feature is etched in the etch layer with the etch plasma. At least one etch plasma parameter is ramped during the etching of the feature to optimize plasma parameters with the changing etch depth and the feature is etched with the ramped plasma until the feature is etched to a feature depth.