Characteristics and Investigation of Reoxidation Behavior on ONO Stacked Flash Memory with Robust Tunneling oxynitride

• Main Authors: Chen-Hsiu Hung, 洪晨修
• Other Authors: Jen-Chung Lou
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/02174313656689376927

碩士 === 國立交通大學 === 電子工程系所 === 97 === In out experiment, we used the oxynitride as the tunneling oxide because the stress induced leakage current may cause the increase of interface-trap density between silicon substrate and tunneling oxide during the programming and erasing cycles for convention oxide. Due to the shallow trap density in silicon nitride trapping layer is very high, this will cause the electrons stored in trapping layer jump by these shallow traps, which is so-called hopping conduction. The electron stored may jump near tunneling oxide and have the higher probability to tunnel through tunneling oxide. Hence, these shallow traps in silicon nitride will result in the degradation of retention characteristics. Therefore, we adopt the reoxidation process after the silicon nitride trapping layer deposited to produce the amphoteric deep trap “≣Si─Si≣”, and it is effective to improve the characteristics of data retention. Furthermore, these deep traps assist to improve the phenomenon of thermal assisted tunneling. Then, the energy band of blocking oxide connecting with nitride for the conventional SONOS structure is smooth. Hence, the carrier tunnel easily across blocking oxide and it will harm the blocking oxide to cause the degradation of endurance characteristics. However, the energy band of blocking oxide connecting with nitride for using CVD TEOS oxide as blocking oxide is steep. The carriers will not tunnel through blocking oxide easily, and that can improve the characteristics of endurance. Therefore, we adopt the CVD TEOS as blocking oxide. We can find the densify after CVD TEOS deposited will also improve the characteristics of data retention.