氧化鉿電阻式記憶體之操作方法與隨機電報雜訊研究

Abstract

本篇論文主要先針對 HfOx-Based RRAM 作 Sweep 與 Pulse 操作下其記憶體特 性之探討，並在最佳化的操作下量測其不同電阻組態並統計分析其 RTN 之累積 密度分佈函數，最終也比較了不同厚度的 HfOx 層造成的 RTN 統計分布的影響。 對於 RRAM 而言，改變其電阻組態的方法有 Sweep 及 Pulse 兩種電性方式， 我們將此兩種方式套用至 RRAM 的 forming 與 Set/Reset 操作中並發現以 Sweep forming 並以 Pulse Set/Reset 的方法使 RRAM 有最大的阻值變化與操作次數。我 們在將 RRAM 操作於不同阻態的過程中量測了 RTN 造成的電流變化，並依電流 大小作統計分析，發現不同厚度的 HfOx 的 RRAM 在各個阻值態下其 RTN 累積 密度分佈函數皆呈現指數分布，在高阻值態下並呈現兩段式斜率。其中 RTN 大 小之平均值皆隨著電阻阻態增加而增加，但是在較薄的 HfOx 層中其平均值變化 較不明顯。

In this thesis, we find the optimized method of operations of the RRAM with sweep and pulse operations. We measured the RTN amplitude cumulative density function (CDF) in different current orders and compared the influences with different HfOx thickness on the cumulative density functions. There are two electrical ways to switch the resistance of RRAM: sweep & pulse. We applied these two ways to the forming & Set/Reset operations of RRAM, and we find the sweep forming & pulse Set/Reset operation method has the best characteristics of memory window and endurance. We measured the RTN amplitude CDF in different current orders in both 60Å and 30Å devices, and the CDF follow a exponential distribution in each current order. The CDF of high resistance states (HRS) have two distribution trends. In both 60Å and 30Å devices, the main distributions follow an exponential trend and the average of RTN amplitude increase with the resistance, but the amount of change is less sensitive to the resistance in 30Å devices.