Method for etching a silicon dioxide layer with a fluorocarbon plasma

摘要

A resist formulation minimizes blistering during reactive ion etching processes resulting in an increased amount of polymer by-product deposition. Such processes involve exciting a gaseous fluorocarbon etchant with sufficient energy to form a high-density plasma, and the use of an etchant having a carbon-to-fluorine ratio of at least 0.33. In addition to a conventional photoactive component, resists which minimize blistering under these conditions include a resin binder which is a terpolymer having: (a) units that contain acid-labile groups; (b) units that are free of reactive groups and hydroxyl groups; and (c) units that contribute to aqueous developability of the photoresist. After the photoresist is patterned on the silicon oxide layer and the high-density plasma is formed, the high-density plasma is introduced to the silicon oxide layer to etch at least one opening in the silicon oxide layer. Preferably, the terpolymer is made up of about 70% 4-hydroxystyrene, about 20% styrene, and about 10% t-butylacrylate.