Impact of CMOS post nitridation annealing on reliability of 40nm 512kB embedded Flash array

The impact of CMOS post nitridation annealing (PNA) temperature on a 40nm embedded Flash reliability is studied. Electrical characterizations of the Flash tunnel oxide are carried out on single cell. These are used to explain the better results in terms of endurance and data retention obtained on a 512kB test chip with a lower annealing temperature. This result can be linked with the decrease of nitrogen in the bulk oxide, improving oxide wear out performance against electrical stress and stress induced leakage current (SILC). The on-chip characterization is, here, an invaluable tool to show the extrinsic behavior in the memory array and apply product-like stress.