Effect of Nitrogen Content in Tunneling Dielectric on Cell Properties of 3-D NAND Flash Cells

Abstract

The effect of band engineering by controlling nitrogen content in the tunneling dielectric of the 3-D NAND flash cells is investigated by comparing various cell properties of the two devices. These measured devices have the same device dimensions and different nitrogen contents. The device with higher nitrogen content shows larger trap density profile and improved erase characteristics. After the same P/E cycling stress, the device with higher nitrogen content shows larger increase of trap density and more significant degradation in its erase characteristics. The electrons stored in the device with higher nitrogen content more easily escape through the trap-assisted tunneling mechanism due to higher trap density, resulting in worse retention characteristics at room temperature.