Read FF Performance Improvement by the Process Optimization in 4Xnm ETOX Nor Flash Non Self-Aligned FG Technique

As the cell feature size shrink of ETOX Nor flash, the non self-aligned FG technique is investigated on account of its improvement in STI/FG poly gap-filling window and effective avoiding the residue caused by FG poly CMP. While, the non self-aligned process has brought about serious bin9 (read FF) failure issue. In this thesis, the failure field and mechanism were located and determined by EFA and PFA technologies. The poor performance of bin9 can be attributed to the cell active area damage due to the surface defects arising during the FG implantation annealing process. The cell read FF performance can be seen significant boost benefitting from the optimized process, in which oxygen is fed through the FG implantation annealing process.