Metal Hard Mask Open Process Window Enhanced by Insertion of Polymer Deposition

Insufficient BARC remaining after TiN etch can result in the CD and profile shift and residue defect issue in MHM open process. In this work, CH₄ deposition is utilized to gain BARC remaining and two approaches for the insertion of polymer deposition were systematically investigated both by simulation and experiment. It is shown that deposition step inserted before BARC etch is more effective for improving the BARC remaining thickness and profile after MHM open. “Visibility deposition” model of the SEMulator3D® semiconductor modeling is utilized to well explain the different behavior of these two approaches and reveal that the high AR and vertical profile of the patterns result in the selective polymer deposition, thus contribute to the BARC remaining improvement. In addition, the process tuning window is also explored for TiN CD and profile control.