Semiconductor die employing repurposed seed layer for forming additional signal paths to back end-of-line (beol) structure, and related integrated circuit (ic) packages and fabrication methods

Abstract

A semiconductor die ('die') employing repurposed seed layer for forming additional signal paths to a back end-of-line (BEOL) structure of the die, and related integrated circuit (IC) packages and fabrication methods. A seed layer is repurposed that was disposed adjacent the BEOL interconnect structure to couple an under bump metallization (UBM) interconnect without a coupled interconnect bump thus forming an unraised interconnect bump, to a UBM interconnect that has a raised interconnect bump. To couple the unraised interconnect bump to the raised interconnect bump, the seed layer is selectively removed during fabrication to leave a portion of the seed layer repurposed that couples the UBM interconnect that does not have an interconnect bump to the UBM interconnect that has a raised interconnect bump. Additional routing paths can be provided between raised interconnect bumps to the BEOL interconnect structure through coupling of UBM interconnects to an unraised interconnect bump.