Experimental study of carrier transport in multi-layered structures

Gate stress measurements are applied to Flash cell array structures. The counter intuitive Vt shift is associated to the charge redistribution in the ONO layer. This redistribution of charge follows Poole–Frenkel conduction mechanisms. In multi-level Flash, the total charge in the nitride layer need to be minimized, and well-controlled, in order to achieve good data retention of the device.