REVERSE MASKING PROFILE IMPROVEMENTS IN HIGH ASPECT RATIO ETCH

摘要

A method of improving high aspect ratio etching by reverse masking to provide a more uniform mask height between the array and periphery is presented. A layer of amorphous carbon is deposited over a substrate. An inorganic hard mask is deposited on the amorphous carbon followed by a layer of photodefinable material which is deposited over the array portion of the substrate. The photodefinable material is removed along with the inorganic hard mask overlaying the periphery. A portion of the amorphous carbon layer is etched in the exposed periphery. The inorganic hard mask is removed and normal high aspect ratio etching continues. The amount of amorphous carbon layer remaining in the periphery results in a more uniform mask height between the array and periphery at the end of high aspect ratio etching. The more uniform mask height mitigates twisting at the edge of the array.