Process design methodology for via-shape-controlled, copperdual-damascene interconnects in low-k organic film

摘要

By dual hard mask (dHM) process combined with sidewall-hardeningetching step, copper dual-damascene (DD) interconnects are fabricated inlow-k organic film without any etch-stop layers under the trench.Careful designs of dHM structures and their patterning sequence enableus to harden the via-sidewall by fluorocarbon plasma, which is a key toreduce final via-shoulder loss at the via/trench connecting region. Thelow-k structure has low via resistance such as 0.65 Ω/0.28 μmΦ-via while keeping the large tolerance of misalignmentin via/trench, appreciable for 0.1 μm-generation CMOS ULSIs