Method for forming a via and interconnect in dual damascene

A method of forming a dual damascene opening, comprising the steps of:

• providing a structure hating 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 90° edges of the first and second low-k layer;
• reflowing the first and second low-k layers to round the substantially 90° edges of the first and second low-k layer within the final dual damascene opening;
• forming a metal layer over the second patterned low-k layer and filling the rounded edge final dual damascene opening;
• and
• planarizing the metal layer to remove the excess metal from the second low-k layer and forming a planarized metal dual damascene structure.

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;
• the first low-k layer being comprised of a material selected from the group consisting of FLARE and polymer;
• 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 nitride layer;
• forming a second low-k layer over the patterned first nitride layer, filling the patterned first nitride layer opening adjacent the nitride spacers;
• the second low-k layer being comprised of a material selected from the group consisting of FLARE and polymer;
• 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 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 first dual damascene opening to form a final upper horizontal interconnect opening;
• the dual damascene opening having substantially 90° edges of the first and second low-k layer;
• and
• reflowing the first and second low-k layers to round the substantially 90° edges of the first and second low-k layer within the second dual damascene opening.

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;
• the first low-k layer being comprised of a material selected from the group consisting FLARE and polymer;
• the first low-k layer being formed by a spin-on method;
• 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 nitride layer;
• forming a second low-k layer over the patterned first nitride layer, filling the patterned first nitride layer opening adjacent the nitride spacers;
• the second low-k layer being comprised of a material selected from the group consisting of FLARE and polymer;
• the second low-k layer being formed by a spin-on method;
• 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 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 first dual damascene opening to form a final upper horizontal interconnect opening;
• the dual damascene opening having substantially 90° edges of the first and second low-k layer;
• and
• reflowing the first and second low-k layers to round the substantially 90° edges of the first and second low-k layer within the second dual damascene opening.

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 FLARE layer over the structure and active device;
• forming a patterned first nitride layer having an opening exposing a portion of first low-k FLARE 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 FLARE layer over the patterned first nitride layer, filling the patterned first nitride layer opening adjacent the SiN spacers;
• patterning the second low-k FLARE layer, and the first low-k FLARE 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 FLARE 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 90° edges of the first and second low-k FLARE layers;
• and
• reflowing the first and second low-k layers to round the substantially 90° edges of the first and second low-k FLARE layers within the final dual damascene opening.