使用二氧化鍺/二氧化鈦介電層之低功率電阻式記憶體之研究

Abstract

科技的日益進步，非揮發性記憶體在我們生活中扮演著重要的角色，快閃記憶體為其大宗，但是快閃記憶體有其微縮極限，因為隨著儲存的載子變少，而使得資料保存及讀取次數的耐久力變差。

非揮發性電阻式記憶體具備低操作電壓、高操作速度、低功率消耗、結構簡單、微縮能力佳等優點，所以，其發展在下一世代非揮發性記憶體備受期待。

我們使用二氧化鍺/二氧化鈦作電阻轉化層製備電阻式記憶體元件來討論元件特性，可以看出，這種以二氧化鍺/二氧化鈦為電阻轉化層的電阻式記憶體元件顯示出在TiO_2上再疊上一層GeO_2，其導通功率為280 μW (70 μA at 4 V)，比起單層TiO_2的導通功率60 mW (20 mA at 3 V)低很多。且操作在0.5V時有大於300倍的低阻態/高阻態電流比。在攝氏85度有大約104秒的資料保存力。其C2C的電流分佈曲線有穩定的係數變化(CV(HRS)：8.3%；CV(LRS)：12%)，這些都是對於未來應用具有良好的潛力。

With the technology development, the nonvolatile memory (NVM) plays an important role in our daily life. The flash memory is considered as the mainstream. However, due to the further scaling limitation, it faces serious challenges, such as data retention and cycling endurance, because of the number of stored carriers becomes fewer.

The resistive random access memory (RRAM) shows a great potential for the next generation NVM application, due to its low operation voltage, high P/E speed, low power and simple structure, etc.

In this Dissertation, we propose a RRAM device using GeO2/TiO2 as the resistive materials. This GeO2/TiO2 RRAM device with extra GeO_2 shows a resistance ratio >300 at 0.5 V, a lower set power value of 280 μW (70 μA at 4 V), compared with TiO_2 single layer RRAM, which set power value of 60 mW (20 mA at 3 V), and good retention with a small HRS/LRS decay for 104 sec was measured at 85oC, and good cycle-to-cycle current distributions, which CV (coefficient of variation) is quite stable (HRS：8.3%；LRS：12%),showing a great promise in future scalable memory application.