Electron Trapping in HfAlO High-κ Stack for Flash Memory Applications : An Origin of V th Window Closure During Cycling Operations
Electron Trapping in HfAlO High-κ Stack for Flash Memory Applications : An Origin of V th Window Closure During Cycling Operations
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用于闪存应用的 HfAlO 高 K 堆栈中的电子捕获：循环操作期间 V th 窗口关闭的起源
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发表时间：
2011
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影响因子：
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通讯作者：
J. V. Houdt
中科院分区：
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作者：
Xuefeng Zheng;C. Robinson;W. Zhang;J. Zhang;B. Govoreanu;J. V. Houdt
耐久性是闪存技术的关键标准之一，特别是对于使用高κ材料的30 nm以上的世代。本文观察到在动态编程/擦除循环操作下，高κ层中的电子俘获导致阈值电压窗口关闭。这种闭合并不源于新陷阱的产生，也不源于擦除期间从栅极注入的电子的进一步捕获。利用最近发展起来的多脉冲技术，发现循环后高κ层中电子俘获的能量分布发生了显著的变化。在较深能级处的电子俘获随着循环的进行而持续增加，因为其在一个编程脉冲内不会达到饱和。在典型的擦除条件下，深能级中的俘获不能被释放，并且深能级俘获的增加也导致浅能级处的俘获减少。得出的结论是，本文中观察到的窗口关闭是由擦除后增加的深陷阱和编程后减少的浅陷阱的组合。
Endurance is one of the key criteria for Flash memory technologies, particularly for the generations beyond 30 nm with high-κ materials. It is observed in this paper that the electron trapping in high-κ layers causes threshold-voltage window closure under dynamic program/erase cycling operations. This closure does not originate from the generation of new traps or from further trapping of electrons injected from the gate during erasing. By utilizing a recently developed multipulse technique, it is found that the energy distribution of the electron trapping in the high-κ layer significantly changes after cycling. Electron trapping at the deeper energy levels continuously increases as cycling proceeds, because it does not reach saturation within one programming pulse. The trapping in deep levels cannot be discharged under typical erase conditions, and an increase in deep-level trapping also causes a reduction of trapping at shallow levels. It is concluded that the window closure observed in this paper is caused by a combination of increased deep trapping after erasing and a reduction of shallow trapping after programming.