First evidence for injection statistics accuracy limitations in NAND Flash constant-current Fowler-Nordheim programming

We present for the first time the direct evidence of an injection statistical spread in the number of electrons placed into the floating-gate of deeply-scaled NAND Flash memories during constant-current Fowler-Nordheim programming. The spread directly affects the precision of the programmed levels and sets the ultimate accuracy of the NAND programming algorithm. Experimental results on technology nodes ranging from 90 nm to 60 nm reveal that the injection statistical spread increases as cell dimensions are reduced and this introduces a new constraint for future NAND memories design.