Trench first metal hardmask post-lithography novel rework process for defectivity and yield improvement

A conventional back end of line (BEOL) post-lithography rework process is usually considered as a non-critical process compared to other process steps in a silicon flow in advanced technologies. This paper discusses the impact of this non-critical process to defectivity and yield. For advanced technology nodes using a tri-layer trench first lithography stack, the conventional rework process was proven to be inefficient. The trench first metal hardmask post-lithography conventional rework process resulted in a massive organic residues from the anti-reflective coating material used. Detailed studies were performed to isolate the source of the defects. Novel dry rework process showed improved performance compared to the conventional wet clean process that has been traditionally used. This novel process has proven to improve yield, manufacturing cycle time and cost.