ETCH APPARATUS

摘要

An etch apparatus. The etch apparatus includes a tank coupled to a recirculating path that includes a dissolver. The dissolver includes a porous carbon matrix filter coated with silicon nitride. An etchant from the tank circulates through the recirculating path and performs a selective etching of a structure in the tank in contact with the etchant. The structure includes silicon nitride on a pad layer that includes silicon dioxide. The selective etching is characterized by the silicon nitride on the pad layer being selectively etched by the etchant relative to an etching by the etchant of the silicon dioxide. The etch apparatus further includes: means for dissolving the silicon nitride coated on the filter into the etchant at a controlled dissolution rate sufficient to cause the selective etching; and means for coating the silicon nitride onto the filter to facilitate the selective etching.