터널 산화막 두께에 따른 Al2O3/Y2O3/SiO2 다층막의 메모리 특성 연구 |
정혜영, 최유열, 김형근, 최두진 |
연세대학교 |
A Study of the Memory Characteristics of Al2O3/Y2O3/SiO2 Multi-Stacked Films with Different Tunnel Oxide Thicknesses |
Hye Young Jung, Yoo Youl Choi, Hyung Keun Kim, Doo Jin Choi |
Department of Materials Science and Engineering, Yonsei University |
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ABSTRACT |
Conventional SONOS (poly-silicon/oxide/nitride/oxide/silicon) type memory is associated with a retention issue due to the continuous demand for scaled-down devices. In this study, $Al_2O_3/Y_2O_3/SiO_2$ (AYO) multilayer structures using a high-k $Y_2O_3$ film as a charge-trapping layer were fabricated for nonvolatile memory applications. This work focused on improving the retention properties using a $Y_2O_3$ layer with different tunnel oxide thickness ranging from 3 nm to 5 nm created by metal organic chemical vapor deposition (MOCVD). The electrical properties and reliabilities of each specimen were evaluated. The results showed that the $Y_2O_3$ with 4 nm $SiO_2$ tunnel oxide layer had the largest memory window of 1.29 V. In addition, all specimens exhibited stable endurance characteristics (program/erasecycles up to $10^4$) due to the superior charge-trapping characteristics of $Y_2O_3$. We expect that these high-k $Y_2O_3$ films can be candidates to replace $Si_3N_4$ films as the charge-trapping layer in SONOS-type flash memory devices. |
Key words:
Charge trap flash, $Y_2O_3$, Tunnel oxide, High-k dielectrics, SONOS |
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