Patent ID: 6440847
Filing Date: 2002-08-27
Classification: H01L

Abstract:
A method of forming a dual damascene opening, comprising the steps of:providing a structure having an exposed active device; forming a first low-k layer over the structure and active device; forming a patterned first nitride layer having an opening exposing a portion of first low-k layer aligned over at least a portion of the active device; the patterned first nitride layer having exposed side walls within opening; forming a second nitride layer over the first nitride layer, lining opening; removing the second nitride layer, leaving nitride spacers over the side walls of patterned first SiN layer; forming a second low-k layer over the patterned first nitride layer, filling the patterned first nitride layer opening adjacent the SiN spacers; patterning the second low-k layer, and the first low-k layer through the opening reduced by the nitride spacers to expose a portion of the active device centered under the portion of first low-k layer exposed by the patterned first nitride layer to form a preliminary dual damascene opening having a lower vertical via opening and a preliminary upper horizontal interconnect opening; removing the nitride spacers and the first nitride layer exposed by the preliminary dual damascene opening to form a final upper horizontal interconnect opening; the dual damascene opening having substantially 90Â° edges of the first and second low-k layer; and reflowing the first and second low-k layers to round the substantially 90Â° edges of the first and second low-k layer within the final dual damascene opening.