Methods for etching a substrate in a plasma etch reactor may include (a) depositing polymer on surfaces of a feature formed in substrate disposed in the etch reactor using first reactive species formed from a first process gas comprising a polymer forming gas; (b) etching the bottom surface of the feature of the substrate in the etch reactor using a third reactive species formed from a third process gas including an etching gas; and (c) bombarding a bottom surface of the feature with a second reactive species formed from a second process gas comprising one or more of an inert gas, an oxidizing gas, a reducing gas, or the polymer forming gas while at least one of depositing the polymer to remove at least some of the polymer disposed on the bottom surface or etching the bottom surface to at least one of chemically or physically damage the bottom surface.