Methods of removing solvent-like residues from wafer backside bevel

During silicon oxide hard-mask-based Al metal line patterning, the imperceptible CFx polymer featured with solvent-like residues around wafer backside bevel area was detected by energy dispersive x-ray spectroscopy (EDS) after conventional cleaning scheme (O2 ashing plus wet cleaning). In this study, additional bevel etching process and wafer pin-up function applied in O2 plasma asher before wet cleaning both could completely remove such solvent-like residues from wafer backside bevel area.