鄰近元件耦合造成之金氧半穿隧二極體雙態電流特性分析

Study of Two-State Current Phenomenon due to Neighboring-Device Coupling Effect in MIS(p) Tunnel Diode

江育誠(Yu-Cheng Chiang)

指導教授 ： 胡振國

國立臺灣大學/電機資訊學院/電子工程學研究所/碩士(2019年)

https://doi.org/10.6342/NTU201901168

摘要

本篇論文旨在探討鄰近元件耦合造成之金氧半穿隧二極體的雙態電流特性分析。此元件為一同心圓的結構，內部的圓形金氧半元件稱之為感應二極體，而外圈環狀結構稱之為儲存二極體。施加負偏壓在儲存二極體後，感應二極體會讀到低電流值。而施加正篇壓在儲存二極體後，感應二極體會回到高電流值，這樣的操作是有重複性的。
在第二章中，我們藉由雙態電流窗戶和保留特性概略的展示了此耦合元件的記憶體特性。藉由儲存二極體區域的電容特性分析，我們得知缺陷電子的抓取扮演了關鍵的角色。儲存二極體的電子抓陷情況影響了該區域的少數載子濃度，而藉由水平耦合效果這樣少數載子的濃度變化會進一步影響到感應二極體的位障。藉由不同的儲存二極體和感應二極體的間距設計，我們可以從電容特性分析得知耦合效果的差異，而這樣的耦合效果差異確實影響了雙態電流的特性包含雙態電流窗戶和保留特性。這樣的結果再次佐證了雙態電流現象是來自水平耦合效果。
在第三章，我們進一步的探討了氧化層厚度對於雙態電流特性的影響。結果發現，較厚的氧化層會使得元件有較大的電流窗戶，但卻會使得雙態電流的保留效果變差，這是兩者的平衡。而最後感應二極體的讀取電壓也是一項優化元件雙態特性的重要影響因素，而我們建議最佳的讀取電壓應選擇感應二極體的電流特性分析之飽和電壓。

關鍵字

記憶體 ； 雙態電流 ； 耦合效果 ； 金氧半元件

並列摘要

In this thesis, the two-state phenomenon in current behavior of coupled MIS device with SiO2 as dielectric material is investigated. The coupled MIS device is separated to two parts. One is the inner circle MIS tunnel diode called Sensor MIS, and the other is outside ring MIS tunnel diode called Storage MIS. By giving a negative stress on Storage MIS the Sensor MIS will read a lower current level, and by giving a positive stress on Storage MIS the Sensor MIS will read a higher current level.
In chapter 2, the overview of the two-state current phenomenon is shown by two-state current window and retention characteristic. The mechanism of this phenomenon is analyzed by the capacitance-voltage characteristic of outside MIS tunnel diode after set and reset. It can be found that the trapped electrons play an important role in the two-state phenomenon. The electron trapping situation in Storage MIS will affect the Sensor MIS read current situation because of lateral coupling effect. Although the trapped electrons are very few, the current is very sensitive to the effective Schottky barrier. The read current will show a current on/off ratio with two or more order. The inference of this mechanism is further discussed with coupled devices with different gap space between Sensor and Storage MIS. The CV characteristics between the two devices show different coupling effects, and the different coupling effects will affect the two-state current behaviors of the two devices.
In chapter 3, the relationship between oxide thickness and two-state current behavior of coupled MIS device is further investigated. It is found that device with thicker oxide will show a larger on/off current window, but a worse retention characteristic. This is a trade-off between current window and retention characteristic. The read voltage of Sensor MIS also affects the current window, and we suggest that the best choice of read voltage is the saturation voltage of the Sensor MIS.

並列關鍵字

memory ； two state ； coupling effect ； MIS

參考文獻

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