The Effect of Passivation SiON Layer on the Data Retention Reliability of NAND Flash

Abstract

Data retention is one of the major device reliabilities of NAND Flash memory. We found that the lower Refractive Index (RI) of the Passivation Silicon Oxynitride (SiON) layer deposited by PECVD, the better data retention behavior was achieved. The hydrogen concentration and the stress analysis of the films are analyzed to find out which is more important in this case. Generally, when the RI of SiON decreases, both parameters also decrease, so it is impossible to find out which parameter is major factor of data retention. To analyze the effects of two parameters separately, we applied two conditions which had the same hydrogen concentration but quite different stress values. The final data retention levels are same in both conditions. In addition, even if the layer has the same hydrogen concentration, the retention characteristic is changed by how hydrogen is bonded in the film. In conclusion, the data retention characteristic can be explained by mobile ions generated by the hydrogen weakly bonded in PECVD SiON films in our experiment.

An Optimized Device Structure with a Highly Stable Process Using Ferroelectric Memory in 3D NAND Flash Memory Applications

“…Subsequently, the etched hole is filled with a dummy material that is easy to etch in the subsequent process. Figure 2b shows the initial stage of the gate replacement process [2] for the electrode formation of the WL. Here, silicon nitride (Si 3 N 4 ) layers and insulating silicon oxide (SiO 2 ) layers are alternately deposited.…”

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Channel Potential of Bandgap-Engineered Tunneling Oxide (BE-TOX) in Inhibited 3D NAND Flash Memory Strings

“…However, the current structure constitutes multiple strings that are extensively used; there exists an inhibited string that does not proceed with program operation. Analysis of the inhibited string is necessary because the channel is not directly connected to the body and can thus easily flow into a floating state, causing various phenomena [12][13][14][15]. Therefore, the analysis of the inhibited channel is as important as that of the selected string.…”

An Improved Structure Enabling Hole Erase Operation When Using an IGZO Channel in a 3D NAND Flash Structure to Which COP (Cell-On-Peri) Structure Is Applied

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