Patent ID: 7570514
Filing Date: 2009-08-04
Classification: B82Y,G11C

Abstract:
1. A method of operating a multi-level cell, the multi-level cell comprising a substrate, a control gate, a charge storage layer disposed between the substrate and the control gate, and a source region and a drain region in the substrate, the method comprising: (a) operating the multi-level cell until a threshold voltage of the multi-level cell is larger than a pre-programming threshold voltage; (b) operating the multi-level cell until the threshold voltage of the multi-level cell is larger than a target programming threshold voltage and smaller than the pre-programming threshold voltage; (c) after performing the step (a) and before performing the step (b), performing a first verification step, wherein if the threshold voltage is smaller than the pre-programming threshold voltage, then repeat the step (a); and (d) after performing the step (b), performing a second verification step, wherein if the threshold voltage is larger than the pre-programming threshold voltage, then repeat the step (b), and if the threshold voltage is smaller than the target programming threshold voltage, then repeat the steps (a)-(d).