Browsing by Author "Shen, Chin-Yen"

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Reliability Study of MANOS with and without a SiO2 Buffer Layer and BE-MANOS Charge-Trapping NAND Flash Devices
(2009)
Liao, Chien-Wei
;
Lai, Sheng-Chih
;
Lue, Hang-Ting
;
Yang, Ming-Jui
;
Shen, Chin-Yen
The reliability of MANOS devices with an oxide buffer layer (MAONOS) in between SiN trapping layer and high-K Al2O3 top dielectric is extensively studied. We conclude that the primary function of high-K Al2O3 is to suppress the gate electron injection during erase instead of increasing the P/E speed. As a result, inserting a buffer oxide only changes EOT but does not change the P/E mechanisms. On the other hand, the buffer oxide can greatly improve data retention by suppressing leakage through Al2O3. However, owing to the slow erase performances with a thick bottom oxide, both MANOS and MAONOS erase slowly and very high erase voltages must be used. Also, both MANOS and MAONOS devices show very fast endurance degradation below P/E<10, which is inherent due to electron de-trapping mechanism. Moreover, the large erase voltage also causes severe degradation of tunnel oxide after many P/E cycling. To get both speed and reliability performances, it is necessary to introduce bandgap engineered tunneling barrier (BE-MANOS) to solve the fundamental problems of MANOS.