Recess structure for padless stack via

A stack layer structure, comprising:

• a capture pad and an inner via formed in an inner dielectric layer, the inner via being stacked over and electrically coupled with the capture pad;
• one or more intermediate vias formed in corresponding one or more intermediate dielectric layers stacked over the inner dielectric layer, the one or more intermediate vias being stacked over and electrically coupled with the inner via;
• an outer via formed in an outer dielectric layer stacked over the one or more intermediate dielectric layers, the outer via being stacked over and electrically coupled with the one or more intermediate vias;
• and
• a cover pad stacked over and electrically coupled with the outer via,
• wherein the stack layer structure comprises a first via and a second via stacked over the first via, the first via being the inner via or one of the one or more intermediate vias, and the second via being one of the one or more intermediate vias or the outer via,
• wherein a top width of the first via is wider than a bottom width of the second via,
• wherein a recess is formed in the first via to partially extend into a top surface thereof, and
• wherein a bottom portion of the second via is within the recess, the bottom portion of the second via extending from a bottom surface thereof up to a height equal to a depth of the recess, the second via being in contact with the first via within the recess.

A method of fabricating a stack via structure, the method comprising:

• forming a capture pad;
• forming a first via stacked over and electrically coupled with the capture pad;
• forming a second via stacked over and electrically coupled with the first via;
• and
• forming a cover pad stacked over and electrically coupled with the second via,
• wherein a top width of the first via is wider than a bottom width of the second via,
• wherein a recess is formed in the first via to partially extend into a top surface thereof, and
• wherein a bottom portion of the second via is within the recess, the bottom portion of the second via extending from a bottom surface thereof up to a height equal to a depth of the recess, the second via being in contact with the first via within the recess.

A method of fabricating a stack layer structure, the method comprising:

• forming a capture pad and an inner via in an inner dielectric layer, the inner via being stacked over and electrically coupled with the capture pad;
• forming one or more intermediate vias in corresponding one or more intermediate dielectric layers stacked over the inner dielectric layer, the one or more intermediate vias being stacked over and electrically coupled with the inner via;
• forming an outer via in an outer dielectric layer stacked over the one or more intermediate dielectric layers, the outer via being stacked over and electrically coupled with the one or more intermediate vias;
• and
• forming a cover pad stacked over and electrically coupled with the outer via,
• wherein the stack layer structure comprises a first via and a second via stacked over the first via, the first via being the inner via or one of the one or more intermediate vias, and the second via being one of the one or more intermediate vias or the outer via,
• wherein a top width of the first via is wider than a bottom width of the second via,
• wherein a recess is formed in the first via to partially extend into a top surface thereof, and
• wherein a bottom portion of the second via is within the recess, the bottom portion of the second via extending from a bottom surface thereof up to a height equal to a depth of the recess, the second via being in contact with the first via within the recess.