NAND快閃記憶體在寫入及抹除狀態下的保存特性之探討

Abstract

本篇論文主要在研究NAND快閃記憶體在經過10000次(10K)寫入及抹除操作後，維持在寫入及抹除狀態下的保存(retention)特性，並探討元件在加熱後，對浮閘中的電子及穿隧氧化層中被捕捉的電子、電洞所造成的影響。我們發現在加熱後，穿隧氧化層中被捕捉的電荷質心位置(charge centroid)不變，電子密度在兩個狀態下加熱後減少的量相近，但電洞密度在抹除狀態下加熱後有顯著的減少。另外，在加熱後，僅一次的寫入及抹除操作亦會使臨界擺幅(SS)及穿隧氧化層被捕捉的電荷有明顯的改變。

In this thesis researching NAND flash memory retention characteristics under PGM and Erase state after 10K cycles. And investigate how baking affect floating gate electrons and oxide trapped electrons and holes. We found that trapped charge centroid doesn’t change after baking, reduction of electron density is close after baking at the two states but reduction of hole density is prominent after baking at Erase state. On the other hand, subthreshold swing (SS) and oxide trapped charges changed obviously after only one more Write and Erase operation.