In the manufacturing of 40nm back-end-of-line (BEOL) interconnects, the chemical mechanical planarization (CMP) process is typically divided into two major steps: bulk copper removal and barrier planarization P1, P2.Following the first step where the copper overburden is cleared and polishing selectively stops on the liner, the Ta-based liner CMP step is executed to remove the remaining barrier metal layer across the field regions P2.This process electrically isolates adjacent copper interconnec