Carbon-doped copper as a high-conductivity liner forcopper/benzocyclobutene (BCB) interconnects

摘要

This work explores the use of carbon-doped copper (Cu-C) as ahigh-conductivity liner for copper/benzocyclobutene (Cu/BCB) damasceneinterconnects, focusing on fabrication of damascene interconnectswithout polish stops and electrical characterization of the Cu/BCBinterface. Single-level-damascene interconnect structures weresuccessfully fabricated with and without a 60 nm Cu-C (<2 at %) liner(resistivity <3.5 μΩ-cm). The RIE removal of the SiN_x etch mask modified the BCB surface both chemically andmechanically with an improvement in adhesion. Electricalcharacterization of Cu/BCB and Cu-C/BCB interfaces usingmetal-polymer-oxide-semiconductor (MPOS) structures shows that Cumigration does not occur at temperatures up to 200° C for 30 minuteswith a bias of up to 1 MV/cm. During I-V sweeps of metal-polymer-metal(MPM) and MPOS structures, instabilities are observed at the Cu/BCBinterface, which do not appear at either the Al/BCB or the Cu-C/BCBinterface